I have done everything possible, starting from reading this : https://support.apple.com/en-us/HT202759
I have set the sync option on the mac , and also on the iPhone/iPad.
When I buy a book outside the Apple store, i put it on my mac, then I would like to be able to see it on iPhone/iPad iBooks , but I just don't see it.
It would be wonderful if I could start reading on the mac and move to the iPhone.
Is it possible ?