Since Salesbox is not a published application on Google Workspace marketplace you need to grant Salesbox the right to connect to your Workspace account from Google Admin Console.
How to make Salesbox:a trusted App:
- Go to Google Admin Console
- Click on Security
- Click on API controls
- Click on Manage 3rd party apps
- Click on add new app
- Search for Salesbox or this ID: 307733726193-vig543i7robg90rit9acadmim07a3dqf
- Make Salesbox a trusted App
Connect Salesbox to your Google:
- Login to Salesbox
- Click on the cogwheel
- Click on Integrations
- Click on the connect button next to the Google logo