You need to find and listen to 40 audio logs, they are the light blue hologron type objects that prompt you to Hold
when near them. There are more than 40 in the game and in my video below, I walk you through 41 collectible audio logs. I would recommend saving after each item because as far as i'm aware you can't replay levels/chapters, so if you miss a group of the audio logs you will have to play the game again.
All the locations contained in the video are shown in chronological order, I hope this helps and most importantly THUMBS UP :-)