During the level “Crash and Grab” you’ll be given the objective to “Locate the squad” and an objective marker will be placed inside of a large monastery near the outskirts of the map.
Continue along as you normally would until you reach them at which point a skipable cut scene will trigger where you’ll all be happy to see one another. Immediately after the cut scene you’ll be inside of a small room with a doorway out and a stairway up.
Start heading up the stairway and continue going up the flights of stairs until you reach the very top and are unable to proceed any further, the achievement should unlock. There are a total of seven flights of stairs to head up.
