This achievement is story related and cannot be missed. It is unlocked at the loading screen following completion of the Main Story mission
Obtain Keys during your third playthrough. This is one of the longer main story missions. The mission begins in chapter 15 and concludes in chapter 16 using the chapter annotation associated with chapter select. Since chapter select becomes available upon completion of the third playthrough and this achievement unlocks during the third playthrough, the best frame of reference is the Obtain Keys Main Story mission.
During Obtain Keys, play alternates between 9S and A2.
Make a save before entering the Amusement Park resource recovery unit. After 9S confronts a boss in the Amusement Park resource recovery unit, play switches to A2. Success in A2's battle triggers a cut scene. The achievement unlocks at the load screen following this cut scene.
If you initiate the Tower Infiltration main story mission without unlocking this achievement, you most likely have experienced a glitch. In the event of a glitch, clear the cache. To do so, turn off the console by holding the
button on the console for at least ten seconds and then unplug the console for at least 20 seconds. Load the save you made at the Amusement Park access point before entering the nearby resource recovery unit. Clearing the cache will most likely remedy the problem and the achievement should unlock at the load screen following the cut scene that comes after A2's fight.