I used the test url suggested under Abantecard extensions for google checkout which I enabled and selected HTML as suggested for sandbox return URL in google checkout, but it does not return.  I also used API version 2 which was recommended by google if I didn't know which one to use, no suggestin in abantecart.  google wallet suggested "https://..." not "http:.." and I tried both, but abantecart has set as http...so a mismatch there. 

Anyway, it doesn't return to the URL when I set it up under google wallet integration for sandbox.  How do I handle this so it will return after purchase with google wallet?

I'm having problems even adding a pdf download; I uploaded a file in pdf form and in zip format and receive incorrect file format or size errors...what's the trick with this?  I added file to downloads and relations and the products set up.