Workspace Administrator (Admin) has the right to add and remove users from workspaces. There may a maximum user limit shown in the user adding interface. If none is present there is no limit.
Managing users is done in the workspace page on the users tab. Type in the new user's email address, select the desired access level and add them.
If the added person does not already have an active user account, they will receive an e-mail from the sender "Inclus <email@example.com>" with instructions on how to activate their account.
Once their account is activate, the person has access to the organization workspace.