it doesn't matter numbers, or letters,... I think the problem is that after paypal donation, the first time the account is created, it may not update the VIP password in the database correctly for the download authorization. But it is fixed by just manually editing your profile with the password again. Many users are not having this problem because they edit the profile, for example to just include the name or avatar in the list of VIP members. And at the same time they fix the password problem without knowing there was a problem. So .. yes.. it's all my fault. Sorry for the inconvenience. I'm not an expert web developer.
I have created a Support page explaining this
https://reaper.hector-corcin.com/support
I'm fixing some things in HeDaMixer today, and adding theme support.