Unfortunately, the documentation says download products only in the lite version. Considering how many other free plugins allow download product it is a shame MP Lite will not allow for complete testing of those kind of products. I did do a 3/4 test where I put a link in the file bucket and then actually purchased that download product thru paypal express. The payment part was great. As the seller, I got an email about the purchase and a copy of the generated download link. The link worked fine.
As a purchaser all I got was a nice you can track your order here msg. Of course I was not returned to the site for a download nor did I ever get an email with the link in it.
It would be nice to be able to test the download feature of MP before committing to the pro version.