Having a debit or credit card on file is necessary for the auction software to function for bidding!

You can update/change/add the card on file via Online Auction Setup > Online Auction Wizard > Run Wizard > skip through to Step 4

Here is the link for changing the credit card for your convenience: 
https://www.biddingowl.com/Manager/Wizard/Auction-Wizard-Step4.cfm