Windows 98? I doubt very much that any current McAfee product would run on that platform.
There were some old McAfee suites which would work on Win98 but you won't be able to get them from McAfee now. If you know what to look for you can find them for sale on eBay; but if you buy from there then you won't have a warranty. Sold as-is, sight unseen, and buyer beware.
I give a link, as an example, to an eBay offer (no guarantee that the product is still available) :
This page (link below) listed a number of products for Windows 98 that were available at the time of writing. The author has made an effort to update the page, and you will see that the range still available is very limited. Some of those said to be still available may not be, it depends on the date the page was last updated.
Good luck with your quest - luck and patience will be needed but you may get something that does what you want.
Since all consumer products changed their updating mechanism a couple of years back there's no guarantee that eBay offer will work for very long as I imagine it wont even update as it's obviously very old.
A good antivirus is one that updates daily to keep abreast of new malware.
So that purchase would be a "caveat emptor" one....let the buyer beware.....
I would say it's next to useless.
It is indeed up to the buyer to decide. There's no guarantee that eBay-purchased old software will work on Win98 but, you never know, it might. It's the only way the poster might get what he wants, anyway.