Q: How to recover old version of Pages app

I just updated my iPad mini 1 to iOS 9.3.4. Before my update,the system suggested me to remove "Pages" temporarily due to insufficient storage. However, when I tried to re-install the app after the update, the status stuck in "waiting" for all the time.

This app was purchased several years ago and when I searched it in App Store, I was no longer to find the app with the same app logo. I wonder if the "Pages" by Apple is the same, but when I opened "Pages" by Apple on my iPhone, I could not find anything related to the old one I have.

I have stored some of my unfinished novels that took me several years of writing  in the app. It would be a great loss if I fail to recover the app, therefore, any of your help or suggestion is highly appreciated.