In release notes, Apple said the update adds support for syncing iOS 11 devices and cleans up or consolidates several parts of the app, including moving iTunes U collections to the Podcasts section and internet radio stations to the music library sidebar area.
You can still find iOS apps, ringtones, and books (PC only) that you've downloaded in your iTunes Media folder. If you want to buy an app for your iPhone or iPad, you'll have to do it via the App Store on the device itself. Seemingly, they're now going back to those earlier roots by removing apps from the latest version of iTunes.
On your Mac, launch the App Store app in your Applications folder. The prompt will tell users that the App Store will no longer be found on iTunes.
Click on the Download button at the top.
You can install iOS 11 now just by signing up for the public beta program on Apple's website. But all of that goes partially to waste if you don't take a proper route of installation of the available update. As confirmed by the company previously, only iPhone 5s and later iPhone models will be receiving the update. iPad models eligible for the iOS 11 update include all the latest iPad Air and Pro models, iPad 5 Gen, and the iPad mini 2 and later.
Books on Windows: Books on iTunes for Windows are managed in iBooks for iOS. It is debatable whether it is a right step by the company to remove the App Store from the iTunes app as more options are usually preferred by us as users.