The achievement is unlocked the first time you view the E ending.
The achievement description is misleading. The achievement does not unlock when you view the final credits. Rather, it unlocks at the black screen immediately following the cut scene that depicts the E ending. This is well after the final credits.
This achievement is associated with viewing the game's true ending. In terms of achievements, though, you might still have quite a few unlocked achievements on the table. No worries provided you heed the caution just below. You can always go back to any save file made after the third playthrough and work towards the achievements you need. You can unlock them through game play using chapter select. Or, you can go to the Resistance Camp and buy them from the special shop by interacting with the seated strange Resistance Fighter.
This entire solution is a NO SPOILER guide with the understanding that it is talking about the end of the game. However, no story spoilers are provided. Nevertheless, it provides you with complete information to help you make the right decisions for you and help you navigate through a rather tricky end-of-game sequence.CAUTION: There is a possibility you could delete all your saves and all your game data. This is part of the game. It is not mandatory nor is it something you can do accidentally because you are given plenty of opportunities to change your mind. However, it is something you can do inadvertently because you do not realize the ramifications of the pod's question.
Bottom Line: If you want to keep your save data, when the pod asks if you have anything to say to other players, answer, "Nope, nothing at all."The pod's question occurs after you unlock The Minds that Emerged achievement. If this is the 47th achievement in the game, you will automatically also unlock Final Words as the 48th and final achievement in the game for completing the other 47 achievements.
If you want to complete the game and do not have the Final Words achievement, do not consider answering Yes to the pod when the pod asks you if you have anything to say to other players. On the other hand, if you unlock the Final Words achievement (signifying that you have a 100% game completion) and do not want to play a New Game plus with your save data; then you may want to choose to answer Yes. If you do so, you will watch your game info--quests, weapons, items, archives, save files etc.--disappear bit by bit from the screen until you are left with a sand-colored blank screen. Later, if you try to play the game, your only option will be to start a brand new game. You will have no data to continue any previous play.
Although this may seem extreme, it is intensely satisfying. You do not have to do this now. You can use chapter select well after you have unlocked all 48 achievements in the game to load Chapter 17-09 and then play through to the point where the pod asks you if you have anything to say to other players. At that point, if you feel you have achieved all your goals, you may answer Yes and sacrifice your game data for the greater good.
Short guide--Recommended approach that shows all possible endings: Choose 9S during your third playthrough and give the first answer to the question at the end of the playthrough for the D ending. Save your game when prompted and load this save from the title screen. Load Chapter 17-09 from chapter select and choose A2 for the C ending. Abort by answering No to the pod's question following the credits. Load the save made at the end of the third playthrough and load Chapter 17-09 from chapter select. Choose 9S and give the second answer to the question 9S is asked. This will give you the second variant of the D ending. Continue by answering yes to the pod's question following the credits. Never give up when prompted during the ensuing top down twin stick shooter fighting sequence. Eventually, the game will intervene and ensure you will prevail. You will get the E ending cut scene. This achievement will unlock right after the screen fades to black.
Short guide--Slightly faster approach that skips a variant of the D ending but has no adverse effect on earning achievements: Choose either A2 or 9S during your third playthrough. If playing 9S give either answer to the question asked. This will give you the third ending. Save your game when prompted and load this save from the title screen. Load Chapter 17-09 from chapter select and choose the character you did not play before. If you are now playing 9S give either answer to the question asked. Continue playing following the credits by answering yes to when the pod asks a question. Never give up when prompted during the ensuing top down twin stick shooter fighting sequence. Eventually, the game will intervene and ensure you will prevail. You will get the E ending cut scene. When the screen turns black the achievement for the fourth ending will unlock as well as this achievement for the fifth ending.
Detailed guide:
To view the E ending, you must have achieved the C and D ending. You get the C ending if you select A2 as the character you control when you conclude the third playthrough. You get the D ending if you select 9S as the character you control when you conclude the third playthrough. Once you have three story endings--A, B, and either C or D--load the save file that was created upon completion of your third playthrough. Use chapter select. Choose the character you did not select during your third playthrough. This will give you your fourth ending and you will now have endings A, B, C, and D.
You now have two choices you can continue on or abort. My recommendation is to abort so you can view the second variant of the D ending. It is slightly faster to continue. You will see only one of the two D ending variants but this has no adverse effect on unlocking achievements. You can abort (by either answering no to the pod's question following the credits, "Knowing that, do you still wish for them to survive?" or by giving up at any point in the twin stick shooter sequence that starts when you answer Yes to the pod's question. If you abort, you will return to the title screen and the achievement for the fourth ending will unlock--assuming that this is the first time you achieve the fourth ending.
If you chose to abort, to view the E ending, load chapter 17-09 and select either 9S or A2. The choice does not matter because you already have both their endings. This time, you will choose to continue.
To continue, answer yes to the pod's question following the credits, "Knowing that, do you still wish for them to survive?" If you chose not to abort the first time you got the fourth ending, the achievement for the fourth ending will not unlock until after you view the fifth ending. Answering Yes to the pod's question triggers a somewhat lengthy top-down twin stick shooting sequence. You are not expected to survive. When you die, you will be asked if you want to give up. Each time you die, the question will be asked a different way but always choose not to give up. You will die quite a few times. Eventually, you will be rewarded for your perseverance. The game will augment your vessel such that you can easily complete the shooting sequence. You will not die if shot in your augmented configuration.
Edited to add 4 August 2018: As
@TheIcemanCometh observes in a comment,
you die quite a few times. Do not be discouraged but always answer the pod's questions indicating you want to continue. After what may appear to be too long a duration, the game will relent and assist you in winning the top down twin shooter mini-game.
A cut scene will follow the shooting sequence when you complete it. This is the game's true ending. When it concludes, the screen will fade to black. Once it does so, this achievement will unlock. Also, if you hadn't earned it earlier, the achievement for the fourth ending will also unlock. If The Minds That Emerged is your 47th achievement, you will also unlock the 48th and last achievement in the game--Final Words--signifying that you have a 100% game completion.
After the achievements unlock, the pods will engage in a dialog. Pod 153 will ask you if you have anything to say to other players. Answer No (or Nope) if you want to retain your data. Answer Yes if you want to retain the data. A full analysis is provided above under Caution. Note that, if you have met the conditions for the Final Words achievement have been met, that it will have unlocked before you must answer your question. This is very important because, if you have not unlocked the Final Words achievement, you will almost certainly want to answer No to the question.