My bad, hotfix re-uploaded, version 2.4.1 grab it when you can.
Remove the old feature set.
Restart blender
Add the feature set again, it should add error-free like normal.
This was simply my fault, bundling up the .zip with the whole plugin at the zip's root, instead of creating a single Rigodotify folder, with everything in it, and zipping that.
Blender is picky, and didn't like it.