This should be the first mission you get the code for. As all documents are given to you before you enter the memory and there are only six scans inside the memory once you've start. You must witness the board in the Filing Cabinnet update itsrlf, Red opens it for you, in order for the achievement to pop
The very first room you ebter has a drone to scan rigjt at the back.
Go upstairs and in to a room with a turned over chair.
In here are two scans one is the rope by the chair and the other is on the left wall as you enter, a piece of cloth in a pipe
Go through to the next room there is a a scan in here too.
Go through thr door and to your left is another door with a scan at the back of the room.
Go downstairs and stealth takedown the guard. Where he was shooting is the final scan.