Just so you know, after you “complete” the game and are returned to the main menu, there’s still a bit of content left, so be sure to continue your save. Though it’s pretty obvious, I still missed it until I started watching a video about the game and realized I wasn’t finished.
MP3Tag + MusicBrainz Picard. I use MP3Tag to set the ID3 tags and picard to move them into the folder structure I want.
It takes a couple hours to set everything up, but I can’t rely on Musicbrainz alone because my music has no metadata on Musicbrainz, so I set the tags myself.