Thanks guys, not sure how I managed to do that one lol. There is now an updated version which fixes this. The permission should have been "helicontrol.dropcrates" but somehow I managed to make it "drop" for the actual check and in the changelog.
Sorry, but the authorization still doesn't exist, man.
Permission 'helicontrol.drop' doesn't exist
It is "helicontrol.dropcrates" not "helicontrol.drop" Shady updated the documentation too. Please update to the latest version and use that permission.