Itunes for the non pc user

In terms of disclosure, i am raising this question obo my 72 old father (a non pc user)

How is one meant to manage itunes when one is an ipad ONLY user.

The current problem is that having preordered a book on itunes, he is now having difficulty in downloading it.

There seems to be no way in which he can view his order history, and no easy means thru which he can identify his preorder and now manually download it to his device.

I have turned on automatic updates (for books) in the hope this may sync, though even this is a concern since it limits his ability to manage his usage, if, for example he deletes a prior book(s) which in turn chews thru his data allowance by resyncing.

Surely Apple recognises that there are and will continue to be many tablet only users who neither wish nor have access to itunes on a full PC.

Having purchased this book via his library/store on his device, surely there is a means by which he can access his history and choose to now install/dl his purchase.

Itunes has deducted the funds from his account, how exactly does he get his actual purchase?

I have even tried logging in on my own device, his preorder does not appear in purchases within the library, accessing his account via the browser indicates no prior purchase history (yes i have found it via logging into itunes on my pc; but that still doesn't help me get it to his device).

It almost seems that Apple is specifically limiting tablet users from fully managing their account relationship from the very devices they promote.

Even some direction on how to identify his preorder and get it to his device would be appreciated.

Thanks in advance.