One can invite team members through;
Settings → Team Management by selecting the role and app(s).
Under a team, users with the following roles are capable of:
Story Creator: Create and edit their own stories & story groups and see reports for their own stories & story groups.
App Owner: Edit and publish any story & story group and see overall reports in their own app(s).
Account Owner: Create, edit and publish any story & story group in an account.