1. Refer to this article below to set up a new Firebase account. (If you have already set up the Admin App, then you can skip this step. It is suggested to check it once again if all steps are completed)
Please note: Both “User” & “Admin” app needs to set up in the SAME FIREBASE PROJECT to get automatically linked with each other.
2. Enable “Phone” Sign-in provider for Users Login. Kindly Refer to this guide: Firebase Authentication Guide