Working with non-profits is something I really enjoy. Groton Bible Chapel is one of my favorites, since it's the church that I call home. About a year ago, we migrated the GBC website over to Squarespace because of the user-friendly backend that allows the staff to make updates on their own.
It's common for people to get hung-up on how to get the social icons on their Squarespace website to link to their Facebook business page and NOT their personal page.
If you do nothing but connect your Facebook account from within the "Connected Accounts" area in the "Settings" menu, then Squarespace will simply link the icons to your personal account. This is the default.