When you first exit Morgan's apartment into the testing labs, you'll find a room called the Simulation Debriefing. This room has a safe in it, and the code to the safe that was written on the whiteboard has been erased.
The code to this safe is 5150. You find it by viewing the video in Morgan's office. If you press your face against the glass while the video is playing and look to the left, you'll see the code not erased.
And that's it. Enjoy your loot!
Prey (2017) Simulation Debriefing Safe Code - GameRevolutionWATCH GALLERY