Let me quickly share with you the latest case study article on Group Leads blog.
The title is: How I Grew My Facebook Group From 0 to 300,000 Members in 6 Months (Without Ads)
Feel free to read it from the link below: https://groupleads.net/grow-facebook-group/
PS: The group now has 522,000+ members. No money spent on ads up till today.