Short answer
HubSpot's KB: a Super Admin sets AI connector access to Sensitive Data at install or reauthorization, and Sensitive Data settings must be on first. Access covers standard Sensitive Data properties (including HIPAA-protected health data) and engagements; Highly Sensitive Data is handled differently. Users still need the matching object and property permissions.
1. In HubSpot
The relevant screen in my demo portal.

2. Worth knowing
Review this before connecting any AI tool in a regulated account.