You sign up for Azure Active Directory (Azure AD) Premium.
You need to add a user named firstname.lastname@example.org as an administrator on all the computers that will be joined to the Azure AD domain.
What should you configure in Azure AD?
When you connect a Windows device with Azure AD using an Azure AD join, Azure AD adds the following security principles to the local administrators group on the device:
The Azure AD global administrator role
The Azure AD device administrator role
The user performing the Azure AD join
In the Azure portal, you can manage the device administrator role on the Devices page. To open the Devices page:
1. Sign in to your Azure portal as a global administrator or device administrator.
2. On the left navbar, click Azure Active Directory.
3. In the Manage section, click Devices.
4. On the Devices page, click Device settings.
5. To modify the device administrator role, configure Additional local administrators on Azure AD joined devices.