Enable Passive Checks on the Windows Host Behind the Firewall
Since this host is on a different network than the Zabbix-Server, and a Zabbix Proxy is not present, we will need to create a firewall rule to port forward external Zabbix Server Passive Checks internal hosts IP and port.
I get the Agents external IP address, and enter that into the Zabbix Server hosts setup for this windows host, and then setup the port forwarding rule on my router.
Zabbix server isn't on the same network as my new Windows host, so the windows hosts internal IP will not work without setting up a specific firewall forwarding rule.
After all configurations have been entered, you can open the services panel on windows and restart the Zabbix agent service so that the agent and server begin communicating.
You may also need to enable a firewall rule on Windows Defender for inbound TCP on port 10050 if it wasn't already created by the Zabbix Agent installer.