The Privacy setting in Conversation settings configures whether people can join the conversation with the Conversation link.
How does it work?
If you want to invite people to the conversation via the link, check the box under the Privacy section in Conversation Settings. Then, anyone with the link can join the conversation (they do need to be signed up as Fleep users to join the conversation):
Prefer to keep the conversation private and not allow for joining with the link? Uncheck the box. Then, new people cannot join via the link, and have to be added to the conversation.
If you have enabled joining with the conversation link, you may also want to turn the Disclose setting on - this will automatically show the message history to new people who join the conversation:
P.S. Once everyone you need in the conversation has joined, you can always disable joining with a link and message disclose.