How does someone outside the club watch, or race?

Two different things:

The public link

For spectators, family, the clubhouse screen.

Set the race's Visibility to Public (Edit, before the gun). A Share this race card then appears on the race page with a big QR code, a Share button, a Copy link button, and the raw URL. Anyone with the link can follow the race live on a map with no login.

The same card is on the tracker itself under the Share panel. Note there is no way to regenerate a public link; switching the race back to Private revokes it.

A guest racer invite

For someone sailing who is not a club member.

On the race page (My clubs → your club → Racing tab → Manage on the race's card), Invite a guest racer → their email → Send invite. You also get a copyable link, which is useful if you are standing next to them. Accepting enters one of their own boats and shares its position for this race only. It does not make them a club member.

Guest invites work while the race is Scheduled or Live. After it finishes the link will not work, so the panel disappears.