Hi. I'm very sorry you aren't able to create an account! Perhaps you should try sending a message to Staff via Special:Contact/bug and see what they can do; I have heard of this issue happening before. Good luck! :)
There probably is an account by that name, but it's probably never logged in at Community Central, hence why there's no userpage. I suggest just trying a different username if you haven't already tried.
A red error message appears above the page if the username has not been taken. If no error appears, it means the username has been taken - regardless of whether the user has edited at Community Central.