I understand how you feel. In my case, as a guest, I can download something 5 times in that one day. And yet, as a member, for some reason, I don't have the same problem that you do. I cannot reproduce the error or issue. I can login, and everything works, except for an occasional minor glitch, which is probably true for every website, at one time or another. Have you checked out or consulted the info on this thread?
https://forums.wincustomize.com/350515/wincustomize-accounts-and-downloading-issues
Stay tuned. It's still the weekend. Hopefully we can get this resolved soon.