I was trying to help a friend install Dropbox on his iPad. He has an account and can access Dropbox via the web, but when he does a search on the Apple App store Dropbox does not show up. All sorts of related apps show up like Dropbox Scan but not Dropbox itself. He said the iPad is 4 or so years old. I have a 9 year old iPad with iOS 9.3.6 that sees the Dropbox download at the App Store just fine but his iPad does not. Any idea why that might be?