the test pages indicated two options for how they might run it.
(1) Register for ballot, if selected via ballot you get a code, use that code to log in and buy tickets
(2) Register your interest, your details are vetted (in some way) and then everyone on the list gets access to buy but still overwhelming demand. The only "code" you need is your registered email address.
Option (2) is similar to how Glastonbury tickets work and it means there is still a kind of reward for effort whilst there being a theoretical limit on the number of purchasers.
The vetting is a mystery but if they say one registration per person etc. and ask for all your personal details, presumably they are then clamping down on people trying to use multiple IDs as sales take place.