Hi Harri. Sorry for the long relay in response.
In order to add (or remove) users at a later time, post-installation, you must run
apcera-setup config again and redeploy the cluster (with
apcera-setup deploy). Note that all users that you create using
apcera-setup will be admins in CE. Also, they will not be able to set or reset their own passwords, as that is only done at config time.
For more secure user management, and to avoid having to
apcera-setup to manage users, I would recommend that you enable and configure Google OAuth2 integration:
You can then use policy to manage users in a more RBAC-like manner and have more granular control of user permissions.