Continue to get message, "Unable to Install 'Pages'" and Numbers and one other app that were formerly part of iOS. iPhone 7. How do I get the apps so that they are useable?

Hello Sunnybill,

Welcome to Apple Support Communities! I see you're having an issue with the Apple apps Pages, Numbers and possibly Keynote and I'd like to help out.

You didn't mention what action was done prior to getting the error message, so I'll give information for updating and uninstalling / reinstalling, which should cover getting these apps working as expected.

Updates available can be found by going to the App Store > Updates tab > Swipe down to refresh > Install any pending updates > Restart after all are completed.

If you can’t download or update apps on your iPhone or other Apple device has steps to follow, including making sure you're connected to Wi-Fi, as cellular data usually has a limit of 150 MB for downloads. I'd also recommend being connected to power during any app updates to save battery.

If you're not able to update any of those apps, you can delete the app and then redownload from purchased items. Make sure you are signed in with the same Apple ID that originally dowloaded those apps at Settings > iTunes & App Store.

Follow the steps in this article to redownload: Redownload apps, music, movies, TV shows, and books

Cheers!