Norton from comcast is compatible with Mac os 10.13. The system requirements have to be updated on the webite and we are looking into it. Please follow the instructions here https://constantguard.xfinity.com/products-and-services/norton-internet-security/
When I click on the link that was sent, I get an "Error 404" message stating "The page you are looking for cannot be found ...", so I still haven't been able to download Norton Security for my new computer.
I just tried going straight to the xfinity website and tried to download the Norton Suite, and the reply I got said something like "No product available for your computer".
See if you have any luck with the following link: