If you have Facebook Account Admin Access Facebook should allow you to generate the required Event Page code (see link below). Back In Squarespace, add an 'Embed' Block to a page. In the 'Embed' Editor hit the '<>'on the right-hand side. Copy and Paste the code from FB to the 'Embed' editor. Click set. You may get a message saying something like 'live stream not available in Edit mode', so hit save. And I'd expect the Facebook feed to be on your page. If I'm overlooking something let me know. It's a good idea.
https://developers.facebook.com/docs/plugins/page-plugin/