The customer authorization (provided in the link you clicked) is out of date, and does not entitle you to use the Blended Threat service.
https://voakl.net/2018/12/03/nzta-have-not-ruled-out-starting-city-centre-to-mangere-light-rail-from-airport-end-first-queen-street-end-wont-start-until-after-2021/