If your website is in the subfolder you need to use general version. I checked edit_translation. It is correct.
It seems that your server doesn't populate $_SERVER['PHP_AUTH_USER'] variable. Please contact your hosting provider and ask them to fix the issue. http://php.net/manual/en/features.http-auth.php
Also you can try to add this line in your .htaccess file
SetEnvIfNoCase Authorization "Basic ([a-z0-9=]+)" REDIRECT_REMOTE_AUTHORIZATION=$1
As a temporary solution you can modify the php code (gtranslate/edit_translation.php file) and disable authentication while editing.