After registering and starting your trial for Shoppable Instagram, you'll be greeted by this screen...
Why do I need to login with Facebook?
Since Shoppable Instagram is a tool for businesses, that means you have your store's Instagram set up as a Business Account. To access Business Accounts, we have to access it through Facebook.
What if I do not have a Facebook?
That's fine, but your store will still have a Facebook Business Account that you can log in and access with a traditional email & password.
What page should I select?
After connecting your account, you'll see a list of every account associated with your Facebook log in. Select the Business Page associated to your Instagram account.