Can't download apps to a child's phone

Hi all,

Until recently, me and my son both had iPhones with parental controls.

He needed my approval for screen time and downloading apps.

When I returned my phone to my employer, it was reset.

Now if my son wants more screentime - I can just tap the parent's pin in his phone.

But when he wants to download an app, it sends a request to the "parent phone" which does not exist.

I tried to find a way to put the pin - didn't find. Tried to approve the request though apple ID on a computer - didn't find.

Please help.

Thanks!