New install. Does not recognize serial number
Are you talking about flow meters? The old Rachio-branded wireless flow meter came with a serial number that was required for the controller to communicate with the flow meter. That flow meter hasn’t been supported for a few years since the newer controllers don’t have the radio receiver circuitry for it. AFAIK, that meter doesn’t show up in the list of flow meters in the app any more, unless you have an old version of the app.
Newer EveryDrop meters come with a serial number, but it’s not required in the app, it’s just used by the company for tracking. Select “EveryDrop 1004/1104” for both wired and wireless EveryDrop meters in the app when setting it up.