We're not sure if that $36.50 will be added to the $50 wager you mentioned. But I hope that's the setup, because that's usually what I'm familiar with, too.
Freebet usually doesn’t include the freebet amount on the payout. The profit made on the bet is the one that can be withdrawn by the players.
Profit should include the bet amount if ever they will count the freebet too on the profit like how the regular bet settled.
There’s no ToS shared on this freebet so most likely it will follow the general rule of freebet.