Actually, if you do get one, you should be able to clear it with a Pixabay License certificate: https://pixabay.com/blog/posts/how-to-clear-a-youtube-conten...

(Disclosure: I work for Canva, the parent company of Pixabay).

You should put a warning on each track. When I first started trying Pixabay the only message for any given track was "Crediting isn't required, but linking back is greatly appreciated and allows music authors to gain exposure." There's nothing warning users that they will more than likely be hit with a copyright notice and will have to follow some specific steps to get around it. That's pretty annoying.