InstaGrow is a stupid experiment that seemed to work better than expected. The idea is to follow as many user as possible, and like as many images as possible in order to get those people to follow you back.
This is the whole magic. But it works like a charm. You will soon follow thousands of users and a bunch of them will naturally follow you back. You may want to modify the script to unfollow all the bad people that did not follow you back.
And please dont take that serious. Please dont take Instagram serious at all. It is just like whoring, nothing more, nothing less.