If the group administrator turns on the function of prohibiting private chat, you can't chat alone or add friends in this group. If the group members are colleagues or have talked alone before, they can still chat alone or add friends.

Group has a function, that is, the group owner can set members in the group to prohibit private chat, and they must add friends before chatting. This purpose is to prevent some people in the group from advertising. Now there is software that can advertise in groups. If chatting is prohibited, the group advertising will be invalid. This is also a way for the group owner to protect the interests of members in the group.