MicrosoftVikramj - I understood BrandonShankss to mean that he wants to stop any of the 50 users outside HR and Accounting from contacting HR or Accounting. In that case as I understand it you need a licence for those 40 users. Or more precisely:
If there are 50 users in total in the organisation
40 standard users
5 HR users
5 Accounting users
If I want to stop any of the 40 users from contacting HR or Accounting, I need 40 licences.
If I want to stop HR from contacting Accounting I need 5 licences.
If I want to stop Accounting from contacting HR I need 5 licences.
So to stop HR contacting Accounting and vice versa, you need 10 licences as you said.
But to stop non-HR/Accounting staff from contacting the protected teams then you need 40 licences.
This makes it very expensive in HE situations where we are trying to stop thousands of Students from contacting a few people. Unless I have misunderstood how licensing works for Information Barriers.
