Hi! A couple things to potentially double-check:
1. Are you looking at the same Airtable base?
2. Are you looking at the same Airtable table?
3. Have you hit "Refresh List" in HubSpot Operations Hub?
In theory, email fields should show up there (in addition to single line text and long text fields)
If it simply doesn't work, alternatively you could turn to Whalesync's Airtable x HuSpot 2-way sync which let's you match on email fields + sync multiple HubSpot objects all at once with linked records/association fields:
https://www.whalesync.com/sync/hubspot-airtable