missing app

Check better if its icon has not been accidentally moved to a different screen page or "hidden" into a folder.

If you still can't find it, check:

Settings>ScreenTime>Content&Privacy Restrictions>Itunes&App Store purchases... the first 3 options should be set to "Allow". When done, restart your iPhone.

Regards

Giulio

Also if running iOS 14 check in App Library in case it was moved there. Just swipe to your last home screen, then swipe once again past it to access App Library.