Are you downloading thru some link the seller provides or are you downloading thru Adobe?
You should have downloaded a trial version before purchasing. That way you save yourself the trouble of pursuing a refund for your purchase. All you would need after getting the trial up and running would be the serial number to make the program work.
As is, Adobe does not provide installation support for older versions of their software, so if no one has any recommendations thru the forums you are pretty much left on your own to resolve the matter with the seller.