The man in the picture is using a caulking gun to seal the joints on the exterior.
The manager showed me the courtyard in the interior of the building, it was the roof of the first floor offices, and was open to the 3 floors of apartments. Running through the center was a walkway, there are going to be chairs and tables put in for the tenants.
The floor is covered in roofing felt and slopes down towards the drains. On the ground floor there are stacks of concrete blocks, they are going to be used to cover the ground, they are going to be placed level, to create a drain.