>>376083001
What you downloaded are raw files, not just the avatar. They'll have .psd files so you can edit the textures and probably some extra .fbx or .blend files for mesh editing.
Go look at sippbox's avatar tutorials for setting up a basic avatar. You may need to use a little bit of trial and error to find what files do what. If you're lucky there will be a unitypackage file that you can slap into unity with the vrchat sdk and upload without any changes.