How can I rename the folder using the *album* tag?

It does. It is even a recommended procedure in the FAQ section of the forum:
/t/8016/1

Folders
And no: MP3tag does not copy files with any action or converter, there is always only one file.
And yes, you end up with nested folders if you use the relative path. It never happens with an absolute path.
So I stick to my advice in post 7.