You need the following information to link your account: App ID, App Secret, Placement ID.
App ID and App Secret: After logging to your Dashboard, go to Basic Settings. App ID and App Secret are at the top of the page.
Placement ID: In the tab Products click on Audience Network. You’ll be redirected to Monetization Manager. In Monetization Manager in the lower part of the page find the Ad Space and click on it. On the next page Placement ID is on the right, click on Copy ID to get it.