The Geovonic Relay Service provides a tunnel through your firewall to allow Geovonic to interact with your internal business systems and ArcGIS Enterprise portal.
The Geovonic Relay Service runs inside your network and opens a secure socket connection to the Geovonic server, allowing two-way communication. This is a common pattern for communicating with secured resources used by applications such as the PowerBI Data Gateway.
Refer to this article for installation instructions.