I only downloaded some games from Reloaded and all of them were OK, but I didn't download much neither I know anything about their ways. They might have decided to add password to archives for some odd reason...
But I'm quite sure there were never any password-protected games on Abandonia. At least I never heard anything about adding passwords to archives. Maybe only some uploaded by mistake.
I don't know really... Maybe some other old member knows something about that.
EDIT: I tried to search the board for the issue you're having. Found only
this. So, try running it in DOSBox, uncheck read-only attribute if it exists on certain executables...
EDIT2: Please move this to Troubleshooting.