Thank you for posting this in Microsoft Q&A.
I understand you are trying to access a driver in their Azure account but is unable to do so because you don't have the necessary privileges. You are specifically asking how to grant yourself the ability to manage Global Admin.
Microsoft Entra ID (Azure AD) Global Admin is a Directory level role, Global Admin Can manage all aspects of Microsoft Entra ID and Microsoft services that use Microsoft Entra identities.
To assign Microsoft Entra roles to users need Privileged Role Administrator or Global Administrator.
For your reference: https://learn.microsoft.com/en-us/entra/identity/role-based-access-control/manage-roles-portal#prerequisites
If you don't have Privileged Role Administrator. I would suggest creating a new tenant for your organization. When you create a new Microsoft Entra tenant, you become the first user of that tenant. As the first user, you're automatically assigned the Global Administrator role.
Follow the steps which mentioned in this document to create a new tenant.
If your organization has already Microsoft Entra tenant, please cross check your role.
To check Microsoft entra roles please follow below steps.
1.Sign in to the Microsoft Entra admin center.
2.Browse to Identity > Roles & admins.
You can see your assigned roles as below image. Click on highlighted link it will redirect to your active assignments.
If you have the Privileged Role Administrator, you can assign yourself as Global Administrator. Otherwise, you have to request the Global Administrator of your organization tenant to assign the Global Administrator role.
Hope this helps. Do let us know if you any further queries.
Thanks,
Navya.
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