With the right software, this is done relatively quickly.
You could use e.g. mp3tag to read the embedded meta tags of your files and then create the necessary folder structure automatically.
But make sure that all your tags already have “AlbumArtist” meta tags.
(This is different than the regular “Artist” tag!)
Each album must have the same content in the “AlbumArtist” tags of all files.
Some details: Telling Plex to ignore music files already processed? - #12 by OttoKerner
