moving files while offline

[iMore Question]

Long story short: I have some non-DRM epub files on my computer that I'd like to read in iBooks (during my commute) on my iPhone SE which runs iOS 9.3.3 even when my phone's not on the internet.

Long story long: There's a monthly cellular data cap on my cellphone plan, and no WiFi in the subway, so just staying online to be able to reach and read an ebook isn't a good option.

The iTunes option to move files between my PC and iPhone with the USB cable looks great in theory. How can I make it work?

On my iPhone, even when the cellular data and/or WiFi is up and running, I get nothing but a "Cannot Connect to iTunes Store" message when I tap the only iTunes icon available.

On my PC, today I downloaded and installed iTunes 12.1.3.6 for Windows from www.itunes.com and connected my iPhone to my PC with the USB cable. I got a "The iPhone 'iPhone' cannot be used because it requires a newer version of iTunes. Go to www.itunes.com to download the latest version of iTunes" message.

Any advice will be appreciated!

 

[BlackNightmare]

When guides refer to the possibility to transfer files through iTunes, they mean the computer software iTunes, not the app on your phone (which is basically only the iTunes Store). If you are prompted with such a message once your phone is connected to the computer, you probably have to update your iTunes version (you can do that through the Mac App Store on a Mac or through the Apple Software Update program on a Pc. Here's a guide to update iTunes: https://support.apple.com/en-us/HT201352).
Once your phone is recognized by iTunes and you can start syncing it, you just have to add your ebooks to the iTunes library and the you can proceed in two ways: "drag and drop" the books you want to store on the device and avoid syncing books, or open the Books tab in the iPhone syncing page and select the books you want to sync. Here's the official guide (it refers to PDFs, but it's valid for every format supported by iBooks, such as ePub):https://support.apple.com/en-us/HT202075