On Team, under Invite someone, enter the person’s email address, pick Editor or Viewer, and click Send invite.
They get an email, “You’ve been invited to join a team on PanoCool”. View invitation in it opens the invitation: they sign in, or create an account, with the email address the invitation went to, and click Accept or Decline.
Until they answer, People lists them as waiting for an answer, and the invitation holds a seat.
They can also answer on their own Team page. Their projects page says “You’re invited to join a team.” with View.
Invite by email only. The person’s name shows under People once they join.
Change a role with the menu next to a person: Editor or Viewer.
Remove… takes a member out of the team, and Cancel invitation… withdraws an invitation, so its link stops working and its seat is free again. Both ask first. A removed member keeps their own account and projects; the projects they made in the team stay yours. To come back, they need a new invitation.
A member leaves with Leave team… on their Team page, with the same result.
An account can be in one team at a time: to join another, it leaves its team first. An account with its own Business plan can’t join a team, and nobody can join a team whose Business plan has ended.