Can I use the Open World Demo Collection in my game and still be allowed to sell my game? I know about the 5% I have to pay to UE4 after a certain amount is made from the game. Just wondering if I am allowed to use it as I’d love to.
You are allowed to use any and all of the free (and purchased) content from the launcher 
you cannot sell them as a package, but you can use them in your game!