Connect an Instagram account to a Facebook Page (via Facebook)
Switch to your Facebook Fan Page
Select "Settings" at the top of screen
Select "Instagram" and click "Connect Account" to add an existing Instagram account to your Page.
Enter your Instagram account's username and password, and select "Log in".
Connect and Instagram account to a Facebook Page (via Instagram App)
Go to your profile and tap icon on top left corner, and tap Settings
Select Account on the list.
Select "Linked Accounts.".
Choose "Facebook" and login.
