So, as the young people say, you join his site, then you buy the book and/or badge which raises the money. Then if you are so minded you undertake the challenges and are awarded points for completion. You do however have to prove you have completed the challenge with photographic evidence which must include the Challenge Book in the picture.
John grants access to the site for those who apply. However he is inundated with people who insist on joining thinking that, despite his pinned post, that it is simply a forum to talk about Triples etc. He warns them about the need to partake or simply contribute to the charity. If they ignore his warning, which they often do, he simply deletes them. That way the only people who can continue accessing the site are those who are contributing and/or doing the challenges. Simples.