Problem description
You are unable to create a DCP Admin
When you try creating a Group Admin, it gives an error that the Email address is used for a non-admin subscription
You have already removed the Non-Admin Alert subscription but still it shows the same error
Resolution
In Druva console, navigate to Reports -> Non-admin subscription
Delete the email from the subscription
Verification
Once an Admin account is created successfully. It will be visible under the Manage Administrators page.