Hello,
Sorry to hear you are having issues. I checked and I can download several Stardock application without issue. I tried Firefox and Edge, both do not show any error for while downloading. Please try again and download using your account product download page: https://store.stardock.com/myaccount/products.

Also, it is best to download one at a time only carry on to the download the next one after the current finished downloading. Do note that the download might be slow.

Thank you,
Basj,
Stardock Community Assistant.