Welcome to the community, @Rob_Lee! :grinning_face_with_big_eyes: Enterprise isn’t an “umbrella” per se. It’s a workspace plan level. For each workspace in your account, you should see a badge next to the workspace name that indicates its plan level. For example, I’ve got one workspace named “Main” that’s at the Pro plan level, and it looks like this on my home page:
Chances are that one of your workspaces has a badge labeled “Enterprise plan.” What you’re paying for with the Enterprise plan is that single workspace, with the unique features available to the Enterprise plan only available to bases inside that workspace. If you want to add another Enterprise-level workspace separate from that one, you’ll have to pay for that separately.
Sorry. It’s been a while since I reviewed the Enterprise plan features, and I wasn’t aware of the “Unlimited workspaces” option in the feature list. It’s best to contact Airtable support directly with account questions.