Please, see if "Google Sync" option is enabled when you couldn't set up a Google Workspace account in Nine.
If you couldn't set up a Google workspace account in Nine with a forbidden error, you should check if the following option is enabled in Google Admin Portal. And if it's not enabled, you can enable it with the following path:
You can turn on Google Sync by checking "Allow work data to sync via ActiveSync."
- Sign in to the Google Admin console.
- Navigate to Devices > Mobile & endpoints > Settings > Universal settings.
- Click Data Access > Google Sync.
- Click the checkbox for Allow work data to sync via ActiveSync to enable Google sync.
- Click Save.
Then, go to your device and then set up the account again.