Vendors who save a payment method that does not have sufficient funds will lose their table reservation at the event they applied for.
What your vendors will see
With AutoPay enabled, vendors’ application process is the same until the Payment Method screen “pictured below.” Here, vendors are given the option to set a card or connect their bank to process the charge if their application is accepted.
Card
For vendors that choose to submit with their card information, the card will automatically be charged when the vendor is accepted by the event organizer.
Bank
For vendors that choose to connect their bank to pay, the bank charge will be initiated when the application is accepted, but the transaction will take 3-5 business days to clear.

Note that with AutoPay, changes to prices of your tables after a vendor application is submitted will not impact the amount that vendor pays with AutoPay. Vendors will be charged the price that you had for your tables at the time of their application, regardless of any changes to the price made after they applied.