You may wish to get a count of the number of an Identity type in your organization for the purposes of accounting for available seat count or simply to have a better idea how many are deployed. This information is available in the dashboard, but depends a little bit on what Identity type you're looking for.
What to do
To get a raw count of the number of Roaming Clients, just go to the Roaming Client page in the dashboard. The total is listed there.
With any other component of Umbrella that's installed as an Identities, go to the Policies section of the dashboard by clicking on Policies on the left hand menu bar. Then click "add a new policy". At this point, a list of components to select will appear including the number of each component already deployed in brackets. There's no need to complete the wizard if you're only interested in getting a count of the currently deployed Umbrella identities. In this example there are 507 AD Computers deployed: