Welcome to my 100% Achievement Guide for Ghost Files (MOAC)!
(Note, When there is no commentary in the video, i had to mute for copyright reasons)
This is quite close to the end of chapter 6.
It is unmissable as we need to do it to get through, but the puzzle itself can be quite tricky to figure out on your own.
Thats where i come into it.
Go to 2:27:05 to see how to do this tricky little number.
Hope This Helps!