If your child asks to buy an app on his/her/their device (even a free one) and you are not getting a notification, here are a few steps to follow: https://support.apple.com/en-asia/HT203025#:~:text=If%20you%20miss%20an%20Ask,re%20on%20a%20supported%20device
Alternatively, the parent can purchase the app on their device and the app should become available to the students in the “family purchases” section as seen in the video above. Direct link to the timestamp: https://youtu.be/QAfHSPggGoc?si=KRkYjTVcSPL551zR&t=272