It's basically the same. Like they said, you just follow the intructions on cloudflare to change the name servers on your registrar and then you're good
Buy your domain with cloudflare, or transfer it over to them. Then just set up dns to point to you server and make sure the proxy switch is on. Pretty sure that's all you need to do at the free tier
The top one ending in 3V66T is a "default" key for Windows 10 Pro. It's not a real valid key, not sure about the others.