Apps within a Qlik Cloud Business Account can only be shared with users that are invited members of your Cloud Business Account. The number of users within your Cloud Business Account is dependent on the number of user licenses you purchase. Apps cannot be shared with free (basic) Qlik Cloud users from a Cloud Business Account.
You should be able to share apps published to your Personal stream (My Stream) with up to 5 users for free.
Apps published to your Business Workspaces or Streams will require paid user access - these seats / user licenses are purchased by the Group Owner and then allocated or assigned to users. ie. they don't have to have their own separate business licenses.
The Group Owner is the person who purchases the initial Cloud Business license.
See below a Help article on the various roles that exist in Qlik Sense Cloud:
I haven't seen any reference to a limit in the number of seats/licenses that you can purchase as a Group Owner.
Hope this helps?