Windows Server 2003 and Ver 1.1.8 of WinLogin

I am trying to protect Remote Desktop login for 2 very old machines that can’t be upgraded for various reasons. I realize that version 1.1.8 of WinLogin is not supported anymore, but I need to protect a WinfowsXP machine and a Win 2003 Server.

I downloaded and installed 1.1.8 without issue on the WindowsXP machine. When I try to install on the Win 2003 Server I get the message “The hostname or keys you have entered are invalid”. I had a look at this article and imported the 2 needed certs. I also confirmed that port 443 is not firewalled, but still get the error when trying to enter the integration key, secret key and API host.

Anyone know anything else I can try?