How to setup a LinkedIn integration
First, be sure that you're not logged into any other LinkedIn account in the browser where you're connecting the integration besides that of the account that you wish to connect. Note that you can still be logged in even if you don't have the LinkedIn site currently open.
Next, navigate to the home dashboard for the campaign where you'd like to connect this LinkedIn integration. Then, choose "Social --> LinkedIn" from the dark navigation bar on the left-hand side of your screen.
Next, click the link in the middle of the screen that says "Connect Account".
A window will then pop up prompting you to login to LinkedIn. Log in with an account that has access to manage the LinkedIn page that you are trying to connect.
You will then be prompted to select the customer account which you would like to connect. Click the radio button next to the appropriate account, then click "Save".
If the account that you would like to connect is under a different LinkedIn account, and you need to enter different credentials to access that account, click the button that says "New Account", then enter the appropriate credentials, and step through these screens again.