@Az Cloud Learner , Thank you for reaching out. The User Access Administrator is a special role usually assigned to the Global Admins of the AAD tenants to provide them access on the Azure Resources.
Azure AD and Azure resources are secured independently from one another. That is, Azure AD role assignments do not grant access to Azure resources, and Azure role assignments do not grant access to Azure AD. However, if you are a Global Administrator in Azure AD, you can assign yourself access to all Azure subscriptions and management groups in your directory. Use this capability if you don't have access to Azure subscription resources, such as virtual machines or storage accounts, and you want to use your Global Administrator privilege to gain access to those resources.
When you elevate your access, you will be assigned the User Access Administrator role in Azure at root scope (/). This allows you to view all resources and assign access to any subscription or management group in the directory.
You can read more about this here: https://video2.skills-academy.com/en-us/azure/role-based-access-control/elevate-access-global-admin
Hope this helps.
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