Growing Facebook Group

I need a couple hundred - couple thousand people to join my facebook group

It doesn't matter if they are real accounts, I just need to boost my social proof

I haven't been able to find a SMM panel that offers group members and you can't boost your FB group with ads

Do you guys have any suggestions / solutions?

Cheers

Youtube video where you invite people to join your private group to get the key or the document or anything else...