Hard to tell from that photo, but the fact that we can see daylight is not a good sign. There should be a metal drip edge piece under the roof metal and a molded rubber closeout that fills the gap. I can't tell if either of those is in place.
This looks like a "carport" structure getting hailed as a garage for cheap. While I know some guys have gotten a nice garage/shop out of these things, buyer beware, you get what you pay for.
I think a pic from outside and another with a wider span would help diagnose the problem. I can't be sure which is the wall and roof and have never seen a wall roof junction like that, appears to be an angle bracket???
I think that is a picture of the underside of a lean-to style roof and it's junction to the wall. If that's the case, it's completely wrong and needs a flashing detail cut into the wall sheeting and a close out gasket.