Of all the Azure IoT Edge modules, the OPC Publisher is one of the more challenging modules to setup. I've had a number of Industrial IoT partners struggle with connecting an OPC UA server, such as a Historian or SCADA system, to Azure IoT Hub using Azure IoT Edge and our open source OPC Publisher module.
So I recently wrote a step-by-step blog post on LinkedIn on how to do this.
If you don't have a physical device to act as the IoT Edge gateway, you can use a virtual machine running on-premise or in Azure as an alternative.
Hopefully the blog post will help you and save you some headaches when connecting using OPC UA.