I assume that the number of folders is already the correct one which means that no new folders have to be created, just the existing ones have to be renamed.
Then I would suggest the following.
First create an action of the type "Format value" for _DIRECTORY (you may have to type it in) with the
Format string: c:\music\%artist%\%album%\
(use an absolute path)
This moves all files to the new location, including the non-audio files.
When that is done, rename the files, and only the files without a path component:
As the files are already in the new folder, only the filename has to be adapted.