When setting up Facebook Sales Channel when accepting:
I see a text box:
Check your extensions or privacy settings to start using Facebook
You might have extensions or strict privacy settings preventing you from connecting to Facebook. Use a different browser or check your privacy settings on Firefox.
I checked for privacy and security and turned off Norton VPN
I appreciate that you have included the exact error message you are receiving, as that is very helpful. Looking into the Facebook Sales Channel, it seems like the reason for the error message displaying is a setting that is preventing the connection between Shopify and Facebook on the Firefox browser. In this case, I would suggest attempting to clear the cache on your browser and try this action once again.
If the issue persists, I would then suggest attempting to use a completely separate browser. As for example, if you are using Firefox - try this action on Google Chrome.