Hi Greg,
The Clive UI won’t work properly in the latest versions of Blender because there have been some breaking changes since that rig was created (about 10 years ago).
The UI script will refer to bone layers that no longer exist.
I’m pretty sure the rig will still work though. Your issue in that regard seems like you have linked it into your animation file, but you haven’t yet create a library override to be able to animate it. (that’s why it doesn’t have a pose mode)
Select the linked object, press F3, type “override” and then choose the first option in list.
That will let you animate it in the current file while retaining the connection to the rig in the other file.
Hope that helps.
