Not able to do group facetime

To use Group FaceTime video calls, you need an iPhone 6s or later, iPad Pro or later, iPad Air 2 or later, or iPad Mini 4 or later with iOS 12.1.4. Earlier models of iPhone, iPad, and iPod touch that support iOS 12.1.4 can join Group FaceTime calls as audio participants.

Are you all running iOS 12.1.4 or later?

~Lyssa

All who take part must have at least iOS 12.1.4 or above, see my previous post.

Otherwise you can only do one to one FaceTime.