He does explain it. He says he uses something called "Callrail":
> By syncing Google Ads with Callrail, your name and address is tied to your click (and all your other data) when you conduct a certain action on a website that an ad directs to. (Clicking a phone number on the website, for example).
And he says he uses Squarespace to add additional data:
> Callrail provides marketers the data that Google would never dare to. Yet Callrail still withholds your IP address (exact location) from us.
> But there’s also an easy way around this: through a website-building software called Squarespace, which costs $12 a month.
> By directing your click to a Squarespace website that uses a Callrail forwarding number, we can see your precise location, including your home address.
I have no idea if any of this works as advertised, but he does explain it.