Explanation
After you've configured an Azure resource with a managed identity, you can give the managed identity access to another resource, just like any security principal.
Use Azure RBAC to assign a managed identity access to another resource
After you've enabled managed identity on an Azure resource, such as an Azure VM or Azure virtual machine scale set:
* Sign in to the Azure portal using an account associated with the Azure subscription under which you have configured the managed identity.
* Navigate to the desired resource on which you want to modify access control. In this example, we are giving an Azure virtual machine access to a storage account, so we navigate to the storage account.
* Select the Access control (IAM) page of the resource, and select + Add role assignment. Then specify the Role, Assign access to, and specify the corresponding Subscription. Under the search criteria area,
* you should see the resource. Select the resource, and select Save.
Reference:
https://docs.microsoft.com/en-us/azure/active-directory/managed-identities-azure-resources/howto-assign-access