You do need to “ipkg install sqlite3” and then you need to change the db-type to sqlite3 in mt-daapd.conf (or via the web interface).
This will cause firefly to build a new database. If you didn’t have any valuable information (other than the songs) in your DB, this is alright.
If you don’t want to lose years and years of listening history and habits, then you might want to convert your database. How to do so has been discussed on the forum, I just don’t have the commands handy 😉