I don't understand the problem you're having. First, JRiver offers a 30 day free trial, so I would like to assume that you downloaded and tried the program before spending your hard earned $50 on purchasing.
If my assumption is right, I'm not sure what downloads you're now having trouble with.
If you can explain in a bit more detail what problems you're having, I'm certain you'll get the help you need to proceed.
This forum (and this company) is the most friendly, and user-centric I've experienced, so please don't give up, just give a chance to receive help.