Poking around (cause the service interests me) it looks like you use their CLI to do everything, including create an account.

https://loophole.cloud/docs/commands/account/login

> Loophole service requires authentication, this command allows you to log in or set up one in case you don't yet have it.

Yep, it creates a link with a code, then proceeds to ask me to "sign in on the web" but does not give me an option to sign up. In the Youtube videos, there's a button to "sign up" but not for me. I've tried with multiple browsers on multiple machines on multiple networks.