I didn't see Jonas' answer because it was deleted. But the link in the comments really helped me understand it better. Can someone undelete the answer? Or explain why it has to remain deleted?
This is the answer in question:
It looks like Schroeder was mistaken that the link was included in your question, you linked to https://keybase.io/docs/chat/crypto, while Jonas linked to https://keybase.io/docs/teams/crypto. Nevertheless, this is still a link-only answer. Since Jonas posted the link as a comment, you're not missing out on anything.
If Jonas would like to edit the answer to explain the relevant parts of the documentation, it can certainly be undeleted.