I can’t see why you couldn’t take the belt to any auto or equipment store and match it up. There is likely some room for adjustment in your unit to tension your belt which would allow some variance in the belts length.
At least it should get you up and running before the new belts arrive. It’s worth a try.
This is what I was going to suggest, having worked in a mom and pop auto parts store in the past. Really shouldn't be a problem...belts are standardized...worst case scenario is that the store might have to order it from the distributor, which means you can get it later that day or tomorrow. You don't want to go to O'Reilly's...Auto Zone...Pep Boys...maybe a Napa or a mom and pop Car Quest store, or the like, where customer service is still delivered.