Do I need Apple Messages to approve child purchases?

After going through some posts in here, reading Approve what kids buy with Ask to Buy - Apple Support and using:

1 Android device to read instructions (and post this)

2 Apple iPads, one for child and one for me (guardian)

1 Android telephone in case the instructions come through SMS or something via Telco...

Having enabled Purchase Sharing

I am still not seeing any messages nor notifications anywhere to approve the purchase of a simple Google Photo app (incidentally, is free and cost $0) which I need to use to backup all my kid's photos because I have to wipe my kid's ipad due to another unrelated incident.

Frankly, I am not sure if I want to spend yet another three hours resolving what should be a simple problem. Maybe Apple decided that I am not a serious part of the ecosystem (I don't use Messages and my SIM card does not sit in any Apple devices).

And to finish off this question, I am prompted to indicate which device has this problem but my child's iPad does not show up on the list.