Whether you can become a member depends on a vote. We now know that becoming a member is not easy. Aside from that, we don’t know much, but we do know that it can be a time-consuming procedure. Going from potential member to actual member can take years. Apparently there are quite a few things that you have to comply with. What exactly? Unfortunately, that remains unclear.
Have you fulfilled all their wishes? Then the members vote democratically. Again, brotherhood plays a major role. If they don’t like you, you won’t get in no matter how hard you try.