Sonoff Zigbee 3.0 USB Dongle Plus -- consensus on installation and use

Just to check, because this passage is confusing me: you are aware that

  • your ZigBee coordinator communicates with zigbee2mqtt only
  • zigbee2mqtt communicates with your MQTT broker.
  • openHAB communicates with your MQTT broker.

So your ZigBee coordinator never communicates directly with openHAB, and there is no configuration of your ZigBee coordinator in openHAB.

If this is a question about how to configure zigbee2mqtt with your coordinator then you may have more luck requesting help from the zigbee2mqtt project.