I recently created a game and used some music that was Creative Commons.
Man, what a pain in the balls it was to find stuff I liked.
Many of the sites that indexed this music had crappy search engines in them. I needed to search for music by key and some sites just didn't do that.
The bigger problems was that the sites felt very bloated and slow to me. And the one I finally found music on (looperman) required an account to download the song files.
I suspect if I didn't have uBlock + Ad blocking in my router, that the sites would have been unusable and suffocating with ads.
I have nothing to really help you with, but I hope you have success making a less shitty resource than what I found for CC music :).