Hack message.

Yes, it is a scam. All such messages are scams from criminals. Do not interact with the message or the sender. Do not download anything based on such bogus messages.

Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

That’s likely an advertisement for a VPN add-on client app, which’ll then have access to all your network traffic should you install it.

As correctly stated above, ignore it. And I’d avoid add-on VPN client apps.

In addition to the above blue-colored link to more info, here’s another Scam Pop-ups, Scam Viruses, Scam Receipts… - Apple Community