One again, the Cloud ODS and API documentation is quite good. There you will find info about ODS / API Admin App.
First Steps in the Admin App
Once you have connected to the Admin App
Notice the demo Education Organizations in the Staging ODS. There won't be any in production yet.
Then go and add a Vendor (for both Staging and Production if you want)
Add an application in Staging (an Education Org will be required)
Save the Key and Secret details somewhere safe
Now we can play with the API
Reports in the Admin App
These reports are best for understanding whether things are where you expect.
Aggregate data only.