Short answer
HubSpot's KB: any HubSpot user who's also a Google Workspace administrator can install the extension. Each user grants HubSpot permission to read and edit their Sheets. Then use Breeze Assistant in Sheets.
1. In HubSpot
The relevant screen in my demo portal.

2. Worth knowing
Ongoing exports to a sheet are a workflow action, not this extension.
3. Related
Google Sheets workflow action.