Instagram uses OAuth to allow users and developers to connect to its API. First time users will have to authenticate by logging into Instagram and authorizing my site to do things using your Instagram account. I won't have access to you or your password, so don't worry about any of that.
The Relationship Test looks at everyone you follow, and everyone who follows you, and gives you a list of all of your relationships (i.e. following, not following, requested, etc.)
If you need to, you can reset your Access Token.