Cantleave, you should receive another email from the website in a couple more days. You will be required to answer questions. The answers can be found in...tada!...a book that you have to buy. It is just another publishing scam.
https://charliekb.wordpress.com/2015/02/02/illuminiat-i-am-not/#comments
Out of curiosity I emailed them, and then got an email back from 'Thaddeus Iam', saying that my membership was being reviewed.
Fast forward a couple of days and I received another email in which they explained that to complete my membership, I had to answer a couple of questions that related to 'Illumination: The First Testament of the Illuminati', unfortunately for them I’m not willing to spend £10 on idle curiosity. However had the book come with a free bottle of wine or a coupon for a free packet of Dairylea or something then I might have bought it.