Reference:
https://docs.microsoft.com/en-us/microsoft-store/acquire-apps-microsoft-store-for-business
https://docs.microsoft.com/en-us/microsoft-store/assign-apps-to-employees

Windows 10/11 Subscription Activation
Windows 10 Pro supports the Subscription Activation feature, enabling users to "step-up" from Windows 10 Pro or Windows 11 Pro to Windows 10 Enterprise or Windows 11 Enterprise, respectively, if they are subscribed to Windows 10/11 Enterprise E3 or E5.

Use MDM enrolment.
MDM only enrollment lets users enroll an existing Workgroup, Active Directory, or Azure Active directory joined PC into Intune. Users enroll from Settings on the existing Windows PC.
Reference:
https://docs.microsoft.com/en-us/mem/intune/enrollment/windows-enrollment-methods

For new internet-based devices, you need to create an app in Intune. Deploy this app to Windows 10 devices that aren't already Configuration Manager clients. This scenario is when you have new Windows 10 devices that join Azure AD and automatically enroll to Intune. You install the Configuration Manager client to reach a co-management state.
Reference:
https://docs.microsoft.com/en-us/configmgr/comanage/how-to-prepare-win10

Reference:
https://www.manageengine.com/mobile-device-management/help/enrollment/mdm_creating_apns_certificate.html Prerequisites for iOS enrollment Before you can enable iOS devices, complete the following steps: Make sure your device is eligible for Apple device enrollment. Set up Intune - These steps set up your Intune infrastructure. In particular, device enrollment requires that you set your MDM authority. Get an Apple MDM Push certificate - Apple requires a certificate to enable management of iOS and macOS devices.
https://docs.microsoft.com/en-gb/intune/enrollment/apple-mdm-push-certificate-get