You will know if the user has not yet activated their account if their user tile details "User Invited". This will update to the user's name once they have completed registration.
As this is from a "noreply" email address, ensure to check Spam and make firstname.lastname@example.org a safe sender to your mailbox.
To manage user invitations:
- Go to Team > Users
- Click the user's tile
- Click Resend Invite to re-deliver an email invitation to the new user
- Click Cancel Invite to remove it from your account and prevent any delivered invitations from being used
- Click Change Role to change the user's role