Xabiton
Cupcake God
I've downloaded several demo extensions without any problems. I know people who have bought quite a few too on both mac and pc. It might just be you.I upgraded to Reason 6,5 and I am having issues with the new rack extensions. they do not download.
I wish when propellerhead announce a new version of Reason that they check to see if the upgrade and downloads work on all platforms.