App shared files not appearing in iTunes

Hello!

I'm new to Apple and iTunes and I've just got myself a new iPad Air 2 which I'm setting up. So far, it's all very nice, but...

I'm having a problem with the "shared files" of apps - where some apps allow you to transfer files directly to them in iTunes. I've a few apps that support this installed, includes VLC and Adobe Reader, but in iTunes none of these apps appear in the "Apps" area. Sync in general seems fine - I everything else syncs OK, and I can see the homescreen of my device in that same Apps window:

That list I've never seen anything in, I've tried reconnecting, restarting, resetting settings, anything I can think of, but nothing appears. All the software, by virtue of just being installed, is presumably the latest versions, and I'm running iTunes on Windows 10 (32-bit).

Have I missed a step somewhere? Is there something I can try to get these shared files to appear so I can transfer to and from my iPad? Is there any other, non-iTunes software that can do this?

Thanks!