Hopefully you did it the correct way.
First use this:
https://help.directadmin.com/item.php?id=648
and after that use this one:
https://help.directadmin.com/item.php?id=629
The directadmin.conf changes will redirect http to https on port 2222 if all is correct.
You can add valid SSL certificates for domains, not for IP addresses. It will not work (in green color) without redirecting to hostname.
You probably did not follow this guide carefully: https://help.directadmin.com/item.php?id=629
You can actually order SSL certificate for IP address too; however this is very rarely used. So go forward with the hostname - it's more easier for people anyway.