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You can leverage the LinkedIn Matched Audiences created by N.Rich during campaign creation by heading to the Target Audience Selection and opting for either to Narrowing down or exclude your audience. You can then select Audiences → Third party → Third party company and you will see all the audiences created by third-parties in your account including N.Rich.
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FAQ
Question: I made changes to my segment in N.Rich, how long does it take for the changes to propagate to the LinkedIn Matched Audience?
Answer: It may take up to 48 hours for any change in the segment to propagate to the LinkedIn Matched Audience. Changes include the addition or removal of accounts to the segment.