Greetings @Maxscian!
For any asset to be published in FAB, it needs to follow the current requirements to the letter:
https://support.fab.com/s/article/FAB-TECHNICAL-REQUIREMENTS
For Music in particular, the guidelines are:
- Minimum Content: At least 5 tracks.
- The product page must contain a way for Fab users to listen to samples of the music.
- Overview Map: Not required.
- Demo Map: Not required.