You put the large blade on backwards, the thick bulge part goes towards the front of the car, the thin part towards the back. That’s what makes the air push the car down. Also you can see the tip of the thin part of the blade sticks out past the winglet
So I got the same spoiler for my car. The bolts for the first step have these O rings in them that prevent me from making the base frame really tight. Is that by design for some reason? Or am I doing something wrong?