Hey there @Riccardo Caranfil 👋
I see you reached out to our Support team and they identified that the error was due to the database being hosted on EU servers. Currently the Firebase / Firestore app only supports US-hosted databases. There’s a feature request to add support for EU hosted databases which they’ve added your vote to. We can’t give any sort of estimate as to when that feature might get implemented but you’ll definitely get an email notification from us once it is!
Sorry your database can’t be accessed via Zapier right now. If there’s anything else we can help with in the meantime, please do let us know.