I've never worked with paypal but I've been struggling with this for awhile now and I can't seem to find a good solution. Sending the user to the payment url works fine and they're presented with the purchase page, price, button etc. Clicking on the payment button also seems to work as they're then presented with the return url. However, after coming back into the Unity Client where the ConfirmPurchase URL is called results in a 'FailedByPaymentProvider Bad Request(404)' error.
I've been through the tutorial several times now (in fact, a bit more detailed examples on this flow would be nice) and can't seem to crack this problem. Any ideas?