CPanel Auto Login is an additional feature for your convenience to log in to cpanel without a password and username. If you face the following error while auto login, it means due to technical reason auto login is stopped temporarily. But your site and cPanle both are live and you can access it manually.
Action Failed Unable to auto-login. Please contact support.
Above error is just saying you that auto login is not working, you can try other way to login to your cpanel.
You can log in to cPanel using your CPanel username and Password.
Check "Cpanel details" email received at the time of cPanel purchase.
It includes your cPanel username and password along with your cPanel login URL.
If you do not know your cPanel URL you can try the following URL.
http://yourdomain.com:2083
Like above add ":2083" at the end of your domain name to access the login page. If your domain is not using our nameserver, or not pointing to correct cPanel it may give you an error. So bets way is to get login URL from the "CPanel details" email.