Enrolment is a separate process from admission.
Admission is the approval to study for a PhD/doctorate whereas enrolment is the administrative process which makes you an Otago student. You must re-enrol for each calendar year of doctoral study.
You must apply to be admitted to PhD study before enrolment is permitted.
Enrolment for first year PhD study is part of the admission application and will be actioned after you have been admitted.