To unlock this achievement, you need to deactivate the 13th orb. To find it quickly, load the 54th checkpoint. The first step is to reach the elevator in the basement with the help of your ''followers''. For the next step, you need to split your followers into 2 groups, 1 group in the upper level and 1 group in the office space. To split the group, use the elevator mechanics, it should be easy to do. Finally, use the office space group to reach the yellow cable and climb up and then, use the upper group to reach the orb (watch the video below):
Office Space achievement:Full walkthrough of the game: