On the left panel select Settings > Advanced Settings. Under the "Pocket or Instapaper" section enter your username and password.
Note: If you select Pocket or Instapaper from within an article (by tapping on the three dots on the top right of the screen) while not being loged in to Pocket or Instapaper the Advanced Setting will automatically swipe up to let you add your credentials.
Open an article. Move your mouse over the share arrow on the top right side of the article. Click the Instapaper or Pocket button. You will be redirected to a login page.