The customer authorization (provided in the link you clicked) is out of date, and does not entitle you to use the Blended Threat service.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://www.nzherald.co.nz/nz/covid-19-delta-outbreak-man-fights-for-vaccine-exemption-after-terrible-eight-weeks-after-first-dose/PZZMFQOP3IM2MGMW3LTHM7A4P4/