Screw just free spins or I'm going insane

Brother owns a 2024 Honda Civic Hatchback and we're trying to install a skirt. Problem is the screw we need to take out free spins and we don't know why lol figured I'd ask this subreddit for advice. TIA! Note: screw mentioned is the bottom right screw in the picture below

Brother owns a 2024 Honda Civic Hatchback and we're trying to install a skirt. Problem is the screw we need to take out free spins and we don't know why lol figured I'd ask this subreddit for advice. TIA! Note: screw mentioned is the bottom right screw in the picture below