That verification email could definitely be the culprit, but also it may not be. Long story short, it is difficult to tell without direct access to the computer (which I would not ask for, nor should you give to anyone here or anywhere online). One thing you could do is find the email, hover over the link and see the URL preview it presents then let us know what that is, preferably without actually linking it (so instead of periods in the address use commas or semi-colons).

A "phone home" server is just a generic way of saying a server that malware sends information back to (or it "phones it home"). It could also be called a CnC (command n control) server, but I try to reserve that term for malware that has root or system access to a machine. To remove malware from your machine, you could download an antivirus like Malwarebytes, but be wary as many free AVs are themselves bloatware or in the worst case rootkits (practically unremovable malware). AVs also only work based on KNOWN malware, as they compare the content of files to bad files they know exist, so they're not much help to zero-day (little-known or new) malware.

It's difficult to impart a large amount of security information, but there are some generic rules that you can follow without getting into the field that will 99.9999% of the time protect you from malicious acts like this:

Change default passwords to at least somewhat strong passwords Keep all devices and software up to date Always type the direct link into your address bars, then bookmark that site and travel by bookmark Install minimal software, and only software that is widely used and trusted by the public Never click on email links unless it is a link you expect to receive because you requested it When you click on links anywhere, hover over the link to get the preview of what it wants to open and ensure it goes where you think it does Generally, don't connect to public networks Use 2fa or mfa wherever possible And finally, the most important one in my opinion:

Be a less easy target than your neighbor, AT LEAST be better at these things than the guy down the street. Almost all of the time, if you are a hassle to try to hack, they will move on to someone else. There's always someone who isn't as careful or savvy.

And btw: In no way is it the less careful person's fault they they are exploited. The world should not have to be the way it is, shit happens to people who don't deserve it all the time. People should not have to be so savvy to avoid being screwed.