Select Setup New System on the Orbi app menu and follow the instructions for getting a new system installed.
Be sure to disable any MAC Address randomizers on phones and pads while at home:
https://community.netgear.com/t5/Orbi-App/NETGEAR-Mobile-Applications-and-Apple-Devices-FAQ/td-p/222…
2nd Option to consider as well. You can setup the new incoming system offline from the ISP services, and set it up manually.
https://kb.netgear.com/22697/How-do-I-install-my-NETGEAR-router-using-the-router-web-interface
While you get the new system setup manually, you can use same SSID name and PW for the wifi on the new incoming system. Once the incoming system is setup, turn OFF any existing RBS and the incoming RBS. Take the incoming RBR to near the existing RBR, Reboot the ISP modem or ONT. While the modem or ONT is rebooting, disconnect the WAN cable from the existing RBR and connect it up to the incoming RBR. Power ON the RBR soon after. When the incoming RBRs front LED stops blinking WHITE and turns OFF, power OFF the outgoing RBR. Your wifi devices that had been connected to the prior existing RBR will auto migrate and connect to the new incoming RBR.
Then power ON the incoming new RBS.
Something I do all the time as I change out systems every so often.