Cant see audiobooks across devices

I am having an issue accessing my audiobooks across my devices. I have a subscription to apple music which I understand allows you to share your icloud library across multiple devices. I am wondering why then I am unable to access my audiobooks from my laptop. These are audiobooks which I have digital copies of and have uploaded to my desktop at home. When I access itunes from my desktop I am able to see them but when I try and acess them from my laptop or phone I cannot see any of the, including ones I have purchased through itunes.

Thanks

R