They take a credit card and at BWV they will charge the card once you put $1500 on it. Or you can choose not to link a credit card to the key and give them money to put on the account to draw from.
There is no set limit, but each level of resort had different amounts of charging the will allow before charging the credit card on file.
Or you can choose to not do anything at all. You don't have to put down money or a card at check in. You do have to pay your balance when you check in though.