Look at the message.
Notice at the top of the window where you see the text "ujd1ml7035.pw". That's the URL that's sending you the message. If something like this were legitimate, it would be from apple.com. Note, however, that Apple would never send this sort of message, and especially not this way.
Additionally, just the overall syntax and sentence structure. It's all clunky and verging on poor grammar. The kicker is Apple allegedly 'requiring' you to download a third party app.Lower res apple logo. The fact it tells you to buy a premium version of something Apple does not sell. Promising to stop all viruses. The address.
This looks like the annual refresher IT training we send out to all hospital staff where I work. You have to find the giveaway clues that identify spam/phishing emails. This would be a really easy one.
Yes, it's always best to double check with others first. Most of my friends just blindly click crap and it's why their PCs have the computer equivalent of the Black Plague.I know that to most of us it's very obviously a scam, but well done to the OP for at least posting here before clicking on stuff.
You knew enough to get it checked out, and now you've learnt something useful. Don't feel bad about posting in future if you get other messages/popups that you're not sure of.