Log into facebook on a computer
Click your Profile Photo in the top right
Click 'See all Profiles'
Select the Page you want to switch in to
Click on your Page's Profile Picture in the top right of Facebook
Click on 'Settings & Privacy'
Click 'Settings'
In the left-hand menu under 'Permissions', click 'Linked Accounts'
Click 'Instagram'
Click 'Connect Account'
Click 'Connect'
Click 'Continue'
Log in with your Instagram Credentials to connect to the Account
And you're done! Your Professional Instagram Account is now connected to your Business Facebook Page.
For Instructions on How to Convert a Personal Instagram Account to a Professional Account, click here: How to Convert a Personal Instagram Account to a Professional Account