The windows need to be broken!

Position yourself against the center of the left round metal structure on the roof and place your crosshair between the two screws at the top of the wall segment like shown. For a fast line up: The correct segment is the one to the right of the second support beam from the left (the ones visible against the sky) of the pipes in the background.

The molotov has some room for errors. Positioning and line up don't have to be spot on.