I don't think there's any roof rack, in this case, though that is the most common place to mount an awning on a medium roof. Pretty sure this uses brackets mounted into the roof rack mounting points. If the awning manufacturer didn't provide the brackets, they are probably custom fabrications.
Note how the front of the awning falls short of covering the front of the slider door. That's because the awning manufacturer specifies a maximum distance of unsupported length, for the end of the awning.
On my build, I added a beefy 80-20 rail on the roof. My main desire was to use a tarp awning. BUT, the rail covers beyond the front of the slider, and it is strong enough that I could / may someday install a true awning to the rail, and it will cover the slider opening.
yeah, that door-open-in-the-rain thing is a toughie. even in really light rains, water runs off the wall of the van above the door and drips into the doorway. seems like there should be a way to do a very small awning (1 foot? 2 feet?) that attaches magnetically to the wall above the door...