Short answer
HubSpot's KB: the card shows on contact, company, deal and invoice records. If you customized the right sidebar or installed after Oct. 7, 2025, an admin adds it. Sync not found means the record isn't syncing.
1. In HubSpot
The relevant screen in my demo portal.

2. Worth knowing
With NetSuite also connected, the KB explains how multiple syncs show.
3. Related
Dynamics 365 integration and the NetSuite card.