When attempting to add another user's (shared) contacts to your own Outlook, you'll notice that you won't be able to access these contacts from the Outlook address book. Additionally, when right-clicking the shared contacts folder, you'll notice you can't choose to display the contacts in the Outlook address book.
The reason for this is that Outlook simply does not allow it. Quoted from an Exchange engineer:
By the current outlook design, itís not possible to implement the shared contacts folder in the Outlook Address Book. The Outlook Address Book tab feature is Ďby designí unavailable for shared contacts folders and this is hard-coded in the Outlook product
However, there do have some workarounds about it:
So basically, if you want to make the contacts available in Outlook address book, and have them available on your tablet/smartphone, the only way is to add the mailbox containing the contacts as an additional Exchange account in your Outlook and on your tablet/smartphone.