There should be a pdf included with the files that can helpfully explain the set up.
But essentially it's this:
- Make sure you have the latest version of VRCFury and the VRC SDK
- There should be a prefab asset in the cage's main folder, it'll be called WLK_CGD or something. That's the prefab to drag and drop onto your avatar. It just goes directly onto the avatar object.
- As for switching between cages, this is done on the ingame menu which is generated if it has been uploaded correctly. If you choose an new option it should save load that by default .
Alternatively you could deconstruct the prefab to not have the other options, but you would need some experience with unity and/or blender to do this.
Hopefully this helps in some way!