When I return to my download page I see and error containing pending_reason=multi-currency
After payment if you see an error message on return containing pending_reason=multi-currency like this this
then this is because you do not have a balance in the currency sent, and you do not have your Payment Receiving Preferences set to automatically convert and accept this payment. You should set your Paypal profile to automatically accept these payments. To do this login to Paypal and click Profile. Click My Selling Preferences and then the Update link next to Block Payments. Check the box next to No, accept them and convert them to USD (or whatever currency you use).