Family Sharing Apps

If you are logged into the same store account on your other phones and have automatic downloads for apps 'on' it will. If the other members of the Share are using their own accounts for the store, which they should be, it won't automatically download as they didn't buy it, they have to go to the Purchased section, select your id there, and download it manually on each device. If they go to the main part of the store they will be charged to buy it on their own accounts

How is it 'not sharing' ? The other members of the Share are going to the Purchased section in the App Store app and have downloaded it from your account there : Share App Store, iTunes Store, and Apple Books purchases with Family Sharing - Apple Support ?

Go to the Purchased section in the App Store app : Redownload apps, music, movies, TV shows, and books from the App Store, iTunes Store, and Apple Books - Apple Support

Or : Share App Store, iTunes Store, and Apple Books purchases with Family Sharing - Apple Support

Did you hide the app? Have they tried signing out of the App Store and back in?

Hide App Store purchases - Apple Support

Family Sharing - If you don‘t see your family‘s shared content