If you are in the US, is it possible to pay the driver on delivery with cash or personal check? I've made a UPS account and entered payment details, but I see no way to assign the shipping invoice to my account for online payment.
Delivery drivers in the US won't take cash. And I am sure they won't take personal checks either. I have been shipping since the 1980s. C.O.D. used to be a popular option but went away a long time ago. Driver's didn't want the responsibility and the risks.
You should find your local UPS office and try to pay there. Might be able to pay at a UPS store.