While logged in to your Facebook page, go to the “settings” tab at the top of the page:
When you are there, find the Instagram tab in the left nav bar:
Here, you will be able to login and link your Instagram account to your Facebook page:
Now, you will have successfully linked your Instagram account to your Facebook page! Doing this will give you access to features like sharing Instagram posts to your Facebook page and vice versa, but most importantly, it allows you to upload Instagram filters to your profile, or give your AR developer permission to do it for you!