I tapped on symbol of cloud w arrow pointing down but app has not downloaded on phone. Help.

Are you getting an error or any prompts after tapping on the download icon?

Try the following:

1. Sign out of the App Store and then sign back in.
2. If that does not resolve the issue verify that you have not enable Restrictions on Installing Apps
3. Verify you have enough free space on the phone
4. Restart your phone and try again