Who is trying to sell you a Firewall? Your computer automatically has one (https://support.apple.com/en-us/HT201642) you should not buy another.

It's possible you have some malware on your computer, that is trying to scam you out of your money. Download malwarebytes (www.malwarebytes.com) and run a full scan. Remove anything you find.

You don't need to purchase a Firewall.

Thank you so much for your helpful reply. We sign up for an Apple Care protection plan and then someone from the company tries to sell me this "firewall protection" haven't got much Apple Care from them so I am looking into it. regards M

Hello Michele,

Please, just stick to what Tyler Downer told you, and stay well away from this :

https://www.pcrisk.com/removal-guides/13623-applecare-protection-plan-pop-up-scam-mac