Can I make commercial use of their game created on the unity free?
Doesn’t matter what version of Unity they used you can’t sell their game without their permission, not ours.
It may be a language issue. “Their game” means “a game owned by them, someone else.” If it’s someone else’s game, drewradley is right. If it’s your game, go ahead and sell it! If you use Unity Free, and you create your own game, yes, you can sell your game commercially.