Microsoft 365 uses Azure AD to manage users and handle authentication and authorization when a user attempts to access an app or data in the Power Platform. You can use either the Microsoft 365 admin portal (https://admin.microsoft.com/Adminportal/Home#/homepage) or the Azure AD portal (https://aad.portal.azure.com) to create and manage users. A user must be assigned a license in Azure AD.
Managing users in Microsoft 365 or Azure AD is out of scope for the PL-200 exam. A functional consultant will not be responsible or have permission for this level of administration.