Everyone here is providing accurate information, it's just not common that people truly understand the world of McAfee products as it exists today, or at least that they feel it's important to realizing how and why you might receive these advertisements in the first place.
Ther following search results were found in seconds using the same DDG search engine you use and display quite clearly why you might receive these McAfee advertisements, since it's a potentially big moneymaker for the affiliate network that McAfee has long cultivated to sell their products. However, since Windows Defender became a free portion of Windows 8 and later, the pressure on sales of 3rd-party products likely has caused a significant decline.
McAfee affiliate advertising at DuckDuckGo
I won't link any of the specific results for obvious reasons, but note that one of the top hits in my case indicated a commission rate of $10/sale, so as it also stated, that's a potentially lucrative opportunity for those willing to promote these on their web offerings, or in fact via any other questionable method such as advertising popups or less reputable, even potentially malicious methods making it appear that malware is already present.
So, all I'm saying is that it's really no surprise that questionable advertising like this exists, it's simply surprising to me that nearly everyone doesn't already know that it does.
Rob