I was also confused about this. Initially I thought I had to create a Google Cloud Platform project for a Google Firebase project. But then I figured out Google Firebase automatically created a Google Cloud Platform project for me.
How to find the Google Cloud Platform project associated with a Google Firebase project:
- Take note of the name of your Google Firebase project from https://console.firebase.google.com
- Log into https://console.cloud.google.com
- At the top of the screen, find the project selector (it's to the right of the "Google Cloud Platform" logo)
- On the "Select a project" window, click the "ALL" tab and there should be a Google Cloud Project by the same name as your Google Firebase project you noted above
What initially confused me was the "Select a project" window defaults to a "RECENT" tab. But when you've just created the project from Firebase's console, it doesn't show up in the RECENT tab of Google Cloud Platform's console.