Hi! Thanks for reaching out.
So, for the music, you have to add new tracks, as the one I have in the game are made by someone else I added tracks with no sound, you just have to replace the files in the engine with the music you want.
As for the collision problem it might be a bug from the upgrade to the 2.3 version. I did not update the project in any major way ever since the release, so not sure I would be able to help you.
If it's not working out with the new version feel free to ask for a refund, it's completely understandable.