Assigning Zoom United licenses via API

I see there are a number of licenses you can assign to a user on a Zoom tenant: /docs/api-reference/other-references/plans. Are customers purchasing United plans actually getting pre-existing license types, or is this plan type missing?

Unable to find license type, or misunderstanding the United plan.

Which App Type (OAuth / Chatbot / JWT / Webhook)?

Which Endpoint/s?

The API for Update a User even has a 300 error reference that talks about a united_plan_type, but I see that nowhere under the request schema: Zoom Meeting API “The value provided for ‘plan_united_type’ parameter is invalid”

How To Reproduce (If applicable)

Screenshots (If applicable)

Additional context
Let me know what else I can read or provide.