It seems that they have reduced the deposit bonus promo, it is no longer "up to $100 USDT" as written in the title of this topic but it is now "up to 50 USDT" only as written in their promotion page.
Since it is 100% bonus and it is limited by "up to", you have explained about it clearly to him.
I'm surprised to see the wagering requirement which is 15x only and it is applied to the initial deposit only.
It means that we deposit $50, our balance will be $100 and we need to wager $50*15 = $750
The question is, which balance will be used first for wagering because there is a casino where the bonus balance will be used first and wager with bonus balance does not count toward wagering requirement.