It’s very easy, you just register on the website and login to the TTY using your preferred SSH shell. Can be Termux, can be Putty, can be a Web SSH, doesn’t really matter. It does require Shell access though.

To be Validated you need to Send at least $1 or €5 to SDF with your shell username written on the envelope or included in the transaction in some way. So yeah there is a membership fee but it’s very cheap.