Hello,
Sorry to hear you are having issues. Recently Stardock have network issue and only come back up recently too. There are still small intermittent issue here and there that creep in now and again. I believe they are still working on it to get it fully working again. We appreciate your patience.
As for your issue, I just tested download Fences 6 and don't have issue with it. Perhaps you can try again or try different browser. Try that and report back.
Thank you,
Basj,
Stardock Community Assistant.