I *think* you need to set up payment zones even though you're not actually shipping anything.
Go to Admin - Locations/Taxes - Zone Definitions. If you really don't care where the person is who pays you, click the "insert" button to create a zone -- call it "Everywhere" or whatever you want. and click "insert" again. Then highlight the Everywhere zone and click "details." It will show no countries, so click "insert" again and it defaults to all countries and all zones. That is just what you want, so click "insert" again.
Now go to Admin - Modules - Payment and select whichever payment method you are using, then click "edit." When you click on "Payment Zone" the dropdown menu should include your "Everywhere" zone. Select that and click "update" and try your payment again.
This assumes you will accept payments from anywhere in the world. If not, call the module something else (maybe Salesarea instead of Everywhere) and you'll need to either add the countries/states one at a time, or add them all and then delete them one at a time. It's tedious, but once you have it set up, you can use that zone over and over.




