Cloud User Hub connects with the Microsoft Partner Center to retrieve a list of the customers you want to onboard.
To verify that Cloud User Hub can access this information, sign in to the Microsoft Partner Center using an account authorized to view customers and manage your partner environment.
Once in the Microsoft Partner Center:
Go the Microsoft Partner Center dashboard
Select the Customers tile
Verify you can view the customers for Cloud User Hub onboarding
If any customers that you want to onboard are not on this list, you must request a reseller relationship with them.