How to buy/install apps (child's watch, no iphone)

I am lost, please help. My kid has an Apple Watch (standalone plan from Verizon) which I've set up as a family watch. He doesn't have an iPhone, and my understanding was that he doesn't need one for the Apple Watch to work.

He has his own Apple ID, which is a member of my family. I can "control" basic settings of his watch, such as Schooltime, from the "Watch" app on my iPhone.

Now, he wants to buy an app. He opens the App Store, finds an app, clicks "Get" or "Buy," and then the Apple Watch asks for his iCloud password. I enter the password on his watch, and then the watch asks to double-click to accept. So I do that. After a few seconds of "processing," it exits to the main clock view.

I don't see the app anywhere. It doesn't matter if I've set up "Ask to Buy" on his account or not. It never asked me for anything, nor is it installing anything.

What am I doing wrong? Do I need to add a credit card to his wallet or something? (My account, which is the "organizer," has a credit card, and I can buy apps on my iPhone or MacBook with no problems.)

The way I imagined it was that he would try to buy an app, and I would receive a message on my iPhone saying that my kid is trying to buy this app, and I would have the option to approve it or not. Is it not like this?"

thank you