authorise computer
When I try to download an audiobook onto my itunes on a new laptop, it keeps telling me I need to "Authorise my computer" from the store. What does this mean?
In order to download, play, or sync content to a device, that account has to be authorised on the computer's iTunes - effectively you have to give iTunes permission to use that account's content (all content that you download from the store is tied to the account that downloaded it). On the current version of iTunes you can authorise your account via the Account > Authorisations > Authorise This Computer menu option e.g.
Authorising a computer : Authorize your computer in iTunes - Apple Support