Why do I need to sign up for InstaChamp with my Facebook login?
The Instagram Messaging API connects to your Instagram account through a Facebook Business Page.

In order for InstaChamp to access your Instagram messages, your Instagram account needs to be a Business Account and that Instagram account needs to be linked to a Facebook Page.
Using a Facebook login to connect to the Instagram Messenger API is a Facebook requirement and the only way to activate automated Instagram DMs.
For a full walk-through of how to connect your Instagram account to InstaChamp superpowers, check out "How to Set Up Your InstaChamp Account."