Mesh question on new install

The new system was delivered last week and I have someone coming next week to help with a rooftop install.

House is approx 4200 sq’ and I want WiFi to extend to yard.

Looking at a few mesh systems and have a question about the setup. I guess I have the gen3 router? Do I need the Ethernet adapter to set this up? When I go to the store in Starlink app I don’t see it as an accessory?