Try this
Create an account which is also hopefully where you are admin of your Webex control hub
Go to developer.webex.com
Under REST apis check out the Licenses and People APIs that will give you what you are asking for.
If your admin rights are correct for your account you may be able to execute the calls in the browser next to the API just to see some REST API calls and results
If you need support you can open a case with developer support.
Thanks
Ashish