By default, your club's page shows a "Request to join" option, letting new players ask to join a specific team themselves (see Requesting to join a club without an invite). If your club would rather only ever add people through direct invites you send yourselves, you can turn this off from Club Settings. The page will then show login only, with no way for a stranger to submit a request.
This is a club-wide toggle, not something set per team.