Short answer
HubSpot's KB: to install a pixel or tag such as the Facebook pixel, Google conversion tag or LinkedIn Insight Tag, connect the ad account first. Once installed it loads on all HubSpot-hosted or external pages with the tracking code, alongside it. Only the user who connected the Facebook Ads account can install that pixel, and installers need Ads Publish permission.
1. Connect first
Ads settings in my demo portal, with no accounts connected.

2. Consent
Pixels follow your cookie banner settings. See consent mode.