This package is aimed for Google Workspace: Domain Shared Contacts. It is not related to People API or Admin Directory API. Notice that Admin Directory API is for internal user accounts, while Domain Shared Contact API is for global external contact directory.
Before using this API, you have to enable Shared Contact in Google Workspace console.
An operation takes 2 or more minutes to spread all domain user's Google Contacts interface. Although it takes seconds to finish an operation at API endpoints.
MIT