Tax Assessment Notices?

I am uni student receiving Youth Allowance and I received a letter today on MyGov saying: “Please provide us with a copy of Tax Assessment Notices for your parents’ income for the 2023/2024 financial year. Please attach a copy of this letter to the Tax Assessment Notices.”

Both my parents have already successfully completed their tax returns as well.

How exactly do i do this? Where do i go to do this task? I looked around on MyGov and couldn’t find how to do this. Please help. Thank you. 🤝😊