I feel so stupid

I downloaded some Kustom icon packs from Play (I have Nova Launcher, moto razr 2023) and now they are sitting in among my apps and I… Uh… Don’t know what to do with them! How do I get them inside Nova Launcher or Kustom Pro so I can use them on screens or at least in a widget? Surely there’s some really easy to do this that noobie me just can’t figure out. Thanks for your time!
PS what’s an APK?

Depending on your license type, you can load a widget directly by opening the widget pack from your apps if you have the separate Pro Key license. If you have the in-app license, open the KWGT Editor, go to Load Presets, then navigate to the Explore tab and select Installed packs.