Unfortunately I can't even get my product feed to successfully upload to Facebook Business Manager, following all of the guides provided to the letter. After going to FB support about the error, they advised that the error was on the Squarespace end. After going to Squarespace support, they have finally replied that the issue is in fact Squarespace:
Thank you for reporting this. I can confirm this is related to an issue with some product data feeds failing to render properly on our end. We’ve reported this to our Engineering team, and they’re currently prioritizing the issue.Please keep in mind that there are many moving parts we need to address before we roll out a solution. We thoroughly test all fixes before they’re released to ensure they don’t affect other Squarespace components or customers.As a result, we can’t guarantee how long it will take to fix issues like the one affecting your site. Also, because of the volume of requests we receive, we can’t always follow up personally when the issue is resolved.
After telling my clients that Instagram products is a feature of Squarespace, and now, when their site is complete, and we are doing this final step in the activation process, I cannot find one person who has successfully been able to get it to work.