Hi Nano, please remember this forum is only for English written posts.
To answer your question, would the whole goal of this app be to drive people to follow you on Instagram? For anyone to engage with what you're doing, the first question you should ask yourself is how you're providing value, whether through content, usability, or something else. I would focus on making an app that creates value as your primary goal rather than an app which goal is to drive followers to your Instagram, as I doubt anyone's interest would be peaked by something like that.