Invitations and invite codes
Invite a person to register or join a team, and understand the difference between the two.
A site invite code permits a new account to be created when registration is invite-only. It does not add that account to one of your teams.
Members can create personal registration invites from the disclosure on the dashboard. Each code is for one person and expires. The page shows the current daily allowance. Share the code privately; it is used when the invited person finishes creating an account.
A team invitation is separate. Team admins send it from the team's Members page to a specific email address. Accepting it gives that account the assigned team role and access allowed by the team's policy. See Create and manage a team.
If registration does not currently require codes, a member invite is still a shareable route into signup rather than a team membership grant. If a valid, unused code is rejected, Contact support.