In order to be able to use the Google Drive API you need to be authenticated. To determine your authentication the APIs request a Token that proves who is trying to use the services and if that configuration has permissions to access the requested API.
Google has different types of authentication. You can use a service account or you can use a Google ID token where you have your Users logging in. You can check more information on the google documentation here.
On forge you have already Google Authentication Core and Google Authentication Management that allows you to do an Google Id token authentication. You can start by configure the Google Authentication Core and create and configure your app in the Google Authentication Management.
On the Google Authentication Management, please add the Drive API Scopes.
After having those configurations you're ready to use the Google Drive integration. You'll need to use the Token that is generated. You can use the actions provided on the Google Authentication Core or provide the token yourself with other authentication methods.
Notes:
In this Integration most rest services apply to Folders and to Files. In some cases we use the same service but separate it in two different wrappers - one for files and the other for folders - to make the use of those actions simpler. If you don't want distinction, you can use the more advance actions from the Shared Drive actions folder