Short answer
The applicant must be the dependent child of an Australian citizen, Australian permanent visa holder or eligible New Zealand citizen.
A dependent child can be under 18, or can be 18 or older if they meet the dependency rules or are incapacitated for work because of bodily or mental function loss.
Home Affairs may need to confirm the parent's Australian citizenship, permanent visa or eligible New Zealand citizen status.
The child-parent relationship can include biological and adoptive relationships, and some relationships arising from artificial conception or recognised surrogacy arrangements. The details depend on the facts and the applicable relationship rules.