...In order to access a Firebase project and its related services using a server SDK, requests must be authenticated. For server-to-server communication, this is done with a Service Account. The package uses auto-discovery for the default project to find the credentials needed for authenticating requests to the Firebase APIs by inspecting certain environment variables and looking into Google's well-known path(s). Once you have downloaded the Service Account JSON file, you can configure the package by specifying environment variables starting with FIREBASE_ in your .env file. ...