Internal, persistent Zoom Team Chat easily lets your search other users by name that have Team Chat enabled at the account level and at the group level. Note that this is different than in-meeting chat. For external users, add them via email address. They need to accept the request to be a contact. That setting to chat with external users also needs to be enabled for you and the far end you're trying to chat with. Those are all permissions to make sure people chat with the right contacts and are allowed by their admins.
