When a user opens Dynamics CRM Online instance manager (https://port.crm[0-9].dynamics.com/G/Instances/InstancePicker.aspx), they see the instance selector if there is more than one instance available but nothing else. The only option is to select the instance and click Open button.
What if you want user to be able to manage CRM Online features but without being a Global Administrator? There is no CRM Online administrator role in O365 portal?!
The answer is Service administrator role.
But wait, there is more: in addition to that O365 administrator role, user needs to be assigned System Administrator role in CRM to have access to the management features per instance basis. That way, user can add solutions to test instance of CRM but without ability to touch the production instance, for example.