This folder is where you should extract the resources from your own copy of Quake 3 to be able to load the maps. And yes, you have to provide your own resources, I'm not going to redistribute id's property. (This works just fine with the Quake 3 demo PAKs, though, if you can dig one of them up!)
As much as I tried to avoid it, there are some changes that you will need to make to the game resources before they can be loaded:
- Any texture files that you need must be converted to PNGs.
- You must make sure that all textures dimensions are a power of 2 (64, 128, 256, 1024, etc)