This example was created in response to this Twitter Question.
- Accessing the database - Get started with Cloud Firestore > Initialize Cloud Firestore > Initialize on your own server
- Getting credentials - Add the Firebase Admin SDK to your server > Initialize the SDK
- Reading data Get started with Cloud Firestore > Read data
Possibly original poster had an issue because they used "Initialize on Google Cloud Platform" section of "Initialize Cloud Firestore" while trying to run their application locally instead of a GCP deployment.