In other words, your organization's PayPal account can not be integrated with ReadySetAuction for in-person check out via @Event > Check Out. However, you can, of course, still check out bidders using ReadySetAuction via @Event > Check Out, email and print the receipt, and then run the transaction directly with PayPal using your own PayPal mechanism.
Prior to your event, have your Administrator include Other as a payment method option. To do this, go to Admin > Event Settings > Payment Methods. Then during check out, choose Other as the payment method.