Why can't i buy books on my iPhone?

Excuse me, I'm having some difficulty purchasing books on my iPhone, and I was wondering if you could shed some light on the situation. I've tried to access the bookstore app, but it seems to be unavailable or not working properly. Could there be any specific reasons why I'm unable to buy books on my device? Perhaps there are certain settings that need to be adjusted, or maybe there's a temporary issue with the app itself. I'd really appreciate any insights or suggestions you might have to help me resolve this issue and get back to enjoying my favorite books on my iPhone.