As an admin of a Space on Knowa you are responsible for adding or inviting new people.
Add / Invite People
To access the administrator area, simply select the Space Settings dropdown in the Private Groups tab of your Space.
To view existing people, select Manage People. Alternatively select Add people to immediately begin inviting - this is simply a shortcut.
Here you can choose to invite new people, or alternatively select people who might already be in another Space within your Organisation.
Note it doesn't matter if you invite as new, someone who is already a user in another space.
See also: Manage people in a Space