How do I setup a LinkedIn account on my Mac OS X Mavericks when I enable two-step authentication within LinkedIn?
The LinkedIn help site have the following section, that also applies to Mac OS X LinkedIn integration:
Some partner applications will simply show an invalid email or password message when you try to sign in for the first time. If you're signing in to one of these applications after turning on two-step verification:
Check your SMS on your mobile device after your first attempt to sign in, to get the verification code. Sign in again using your password followed by the verification code (with no space in between) that was sent to your mobile device.