It is exactly the same. Download one of the clients, for example, Element. Then register. You don't even need an email address. Just make up a name, and a password.
There's even a web client that is functionally identical to the desktop and mobile clients.
It could not be simpler.
Ta da.
He's not talking about himself, he's talking about (non-IT) friends and family. Most of them probably would be barely able to find the register dialog on HN, that's at least what I would say about my non tech-savy friends. A good chunk of them doesn't even have a PC.
For those people, Signal is optimal. Its onboarding and usage is a lot easier than Matrix.