Continuous McAfee Security Alerts!

I keep getting security alerts every few seconds! I DO NOT have McAfee installed on my computer or any subscription with them. I saw that someone else here has the same issue and I followed suggestions given to them such as opening Safari settings/websites and blocking that site but McAfee is not on the list. My Mac is up to date on software and I have run security scans with Norton and nothing bad shows on the reports. When I open one of these alerts, the first screen states my computer is at risk (below). If I click outside of that alert box the next screen shows and states that I am protected. I tried clicking on the settings and help buttons on that page and nothing happens. How do I stop this?