Hello, Melodyyy! Although I am not familiar with those specific ads, I do know they are not connected or affiliated with FH in anyway that I know of. It sounds as if your computer has picked something up. Did you accidentally download off of an ad when you were clicking a link from the forum? Which site were the map/Feralheart modifications downloads from? Was one of them Mediafire, or another site?
I'd recommend downloading an antivirus or another form of security protection and scan your computer as soon as possible. If those ads are popping up randomly, even when you're not on an internet browser (or a site redirects without any warning), there's a possibility you may have picked up some sort of adware. You could also do some research on your problem to find specific help for your issue. Best of luck to you!