i couldnt sync my purchases between my apple devices

dont like this app, i bought a book via iPhone and couldnt download it on my iPad and Macbook. no sync - no stars. why i should buy and pay money for the same books with the same apple id from each device, i dont understand this??????? and one more i wrote to the customer support twice and didnt receive the answer!

wiktorek2010 about Аудиокниги Слушай в Loudbook, v2.2