Searching books on ibook app

I have one old ipad mini with ios version 9.3.6 and ibook version 4.8. Recently I was not able to update the software or any of the apps from the app store. I want to use the ibook app for reading the book and hence started searching the book and found it is not able to search books from library hence I am not getting any books now from the ibook library. Need support here to make use the ibook and to access the library so that I can utilize this book for reading.