Connecting Google Sheet and CRM via flow

Hello. I'd like to copy records from Zoho CRM to an online sheet (Google Sheets, but it could be Zoho Sheet if it's easier). I want the right information in Google Sheet, so the flow needs first to check if there is a row to update in the sheet, and if there's not, then create a row.

Configuring Zoho Flow, in the "update row (new)" action, the only option that seems related to finding an existing row is "Row number". Does this need to be the number of the specific row? It can't be a unique value, it has to be the number?

If it has to be the number, I don't understand how Zoho CRM could store the number of the corresponding row in a Google Sheet.

Can you help me with this? The documentation doesn't explain how to update rows.

Thanks.