I've typed in my Username (it automatically shows my first and last name) and I've entered my Adobe password. I've also tried typing in my email address as User name and it still doesn't go through, the box just vibrates. I'm not tech savvy, just trying to download Flash Player.
This is the operating system, not Flash Player, prompting for the information, as such this is the UserID and password you use to log into your system (if your user ID is not an Administrator, you'll need to provide that). See What userid & password do I need to install Flash Player? for more information.