Atlassian Team members are employees working across the company in a wide variety of roles.
May 20, 2019 edited
You can add outside Guests to single boards in order to collaborate on your team boards. It is not required that all members are on a team. If Guests are added to a single board within the team, the guest is free of charge.
To be transparent though, if you add users outside your team to more than one board in your team, the Multi Board Charge will apply: Multi-Board Guests. Guests that are just on a single board in the team are free of charge.