I'll suggest https://tallbeard.itch.io/music-loop-bundle, https://xdeviruchi.itch.io/8-bit-fantasy-adventure-music-pack or https://not-jam.itch.io/not-jam-music-pack as some great free music here on itch that I've used before in my projects. You can also look at https://itch.io/game-assets/tag-music and https://itch.io/soundtracks if you want other options.