I don't think you can have subfolders.  When you add a folder in the browser, it asks for the type of shader the folder contents is.  Subfolders is not a type.  I have not bought the art of shaders collection.  I'm surprised that there is not a read me with it.  I don't think I've seen a DAZ download that didn't have one.  Did you check your Carrara folder for a readme file?

Irene

Irene-