You will find it helpful to watch several scooter belt change videos on youtube.
You'll need a small wrench or socket set to remove the belt cover....then your impact gun can remove the forward pulley nut, and the rear clutch nut.
You'll need a holding tool to refit this larger 2 nuts - as your impact gun could easily overtighten and strip them.
If this is your first belt-change-rodeo, seek assistance from a local scooter person - or watch
a whole bunch of the belt change videos to see what you'll need to do....and the kind of tools you'll need.
Ask as many questions here as you need to....we're not going anywhere right now
Stig