I really think, and I've said this before, that there needs to be a way for people to join guild/party/settler groups, well, perhaps not settler groups, but certainly the other two, without direct contact.
Couldn't there be a place in the starting cities that, like the citizen 'book' allows players to request membership of a guild or settler group?
Otherwise the only real recruitment methods are through the forum, discord or by someone seeing a player in game with a guild name above their head.
This is done on purpose, so actively inviting a member into a guild/party, etc requires the characters meet face to face in game with a Guild Leader/Officer or Party Leader/Officer. You can soft recruit outside of the game, but that initial meeting in-game is required to join.