Charities
Registered charities go on the link for free.
Everybody else pays $105. You pay nothing, and you are not treated any differently once you are on.
You will probably be outbid quickly. That is the offer rather than the catch, and it is worth being straight about. The homepage is the half of this that is temporary. Somebody will pay to take it, maybe within the hour.
The other half is permanent. You get the next owner number, a certificate saying which one you are, and a row in the ownership history that stays there, still clickable, for as long as the site exists. Nobody can outbid that. It is the part buyers are actually paying for, and a charity gets it for nothing.
What to send. Get in touch with the website you want linked and your registered charity number, so it can be checked on the public register. That check is the only condition.
The rules still apply, and they are the same rules as for anybody who pays. There is no cost, now or later, and nothing to cancel.