UE4 for non-commercial games

I briefly looked through the EULA, but didn’t see anything about this. I was wondering, if I use UE4 to make a non-commercial indie game, would I need to pay anything aside from the $19? My apologies if this has been asked a million times or is a stupid question.

If the game is free for the end user, you do not have to pay any royalty.

unless you make money from it in another way, for example if you put adverts in the game and you make money from them even if the game is free you would still have to pay royalties.

Great answers - thank you both.