urgent rush! Tenant wants to pay with credit cards (not scam)

I am not merchant, how can they do that?

Pls advise immediately. 

Not a scam, they just pay the final rents before move. But(i guess) they only have credit card, and they want to use as a purchase on credit card. 

I am in Canada, it shall be the same. Can they buy money orders with credit cards somewhere?