This quick blog will show you how to link your Facebook Business Page to your Instagram account for sharing. This was done using an iPhone 6+ phone so might be different on other phones.
Click on the options icon from your main page on your smartphone that looks like a gear in the top right corner.
Select the Linked Accounts option which is about half way down the page.
Select the Facebook option. It might require you to authorize the app but should get you to your personal Facebook page first.
Select the “Share to” option which should currently say Timeline (Default). You might be required to authorize the app again to allow for advanced settings.
Now you should be able to select the Facebook Page you want your Instagram Photos to share to when selecting that option to post on Instagram.