Prerequisites
You'll absolutely need these before starting with below guide:
A service account (see https://www.spencersupport.com/post/set-up-user-sync-with-google-workspace under "Create a Service Account")
A generic Spencer user account that has impersonation permissions (see https://www.spencersupport.com/post/set-up-user-sync-with-google-workspace under "Grant a generic user read rights to impersonate").
Enable GDrive API
#1 Navigate to https://console.cloud.google.com/home/dashboard and open the Spencer specific project. Click the button called Enable APIS and SERVICES.
This loads following screen:
#2 Enter "drive" in the search bar:
#3 Click on Google Drive API, which opens a details screen. Click on ENABLE.
Add scopes to the generic user account
#1 Browse to https://admin.google.com, login and navigate to Security > Overview.
#2 Scroll down, search for API controls and click on it.
#3 Click on Manage Domain Wide Delegation.
#4 Select the row with your API client created earlier and click Edit.
Add following scopes and click Authorize:
At last, you've reached the end!
Please inform Spencer that you've completed the steps so they can activate the document library integration on their end.