You can always try youtube to try to search up links. If not, you can always convert the youtube to an mp3 using an online source! iTunes possibly might have it too (I’m not sure about this). I’m sorry for not being much help!
This is another admin and I found this. There is a list of songs by other artists that feature Epik High members if you scroll down a bit. I’m pretty sure that this doesn’t include every single song, though, because it’s outdated. And I don’t think very many of the links work, but I didn’t check. I hope this helps!