Hello vdev1n,
Thank you for using Apple Support Communities.
It sounds like you’re having trouble downloading a specific app on your iPhone. If you have not already, we recommend restarting your iPhone to see if that helps.
If not, try the steps in this article:
If you can’t download or update apps on your iPhone or other Apple device - Apple Support
Lastly, if you haven’t already, you may want to try signing out of, and then back into the App Store. You can do so by tapping Settings > iTunes & App Stores > [Your Apple ID] > Sign Out.
If the issue persists, you’ll want to contact Apple Support.
Best regards.