You have installed FCKeditor under a directory restricted with authentication.
You can either remove the authentication (probably an .htaccess file tweaking a few lines there, not a good solution from my point of view), or move it to a place where that restriction doesn't apply (but make sure that only the people that has the proper credentials can use the editor, don't rely on putting it in a place "where no one will find it")
RE: Asking for Username/Password
You can either remove the authentication (probably an .htaccess file tweaking a few lines there, not a good solution from my point of view), or move it to a place where that restriction doesn't apply (but make sure that only the people that has the proper credentials can use the editor, don't rely on putting it in a place "where no one will find it")