I just realized the gui says "choose skins resource file".
But if you hover there it does say "path to the skin to use". It it simply talking about the .vlt file you downloaded and put into that skins2 folder.
You have to go choose a skin file to use there. And once you're in skinned mode most of them bring up a direct list of skins that are available in that folder and it's easy to choose, you don't have to go seeking files.
But beyond that, you don't have to deal with anything, which is what I was thinking about, because a skin package (vlt file) is made up of various resources and literally what would be called a "skin resource file". But you don't have to worry anything about that stuff for just using skins, it's all automatic.