New to TikTok - Copyright question

Hey so i just started with TikTok and was wondering how it works with the Copyright since i already made some vids for YT shorts which use copyrighted music so it has a revenue share and all that from what I've heard TikTok just give the creator 100% but I'm actually fine with this but i also heard that you can't upload the music with the video since it could get muted and instead you have to use like the TikTok library wanted to know if all that is true?

Thanks for everyone reading this to then end!