Here you can customize the opt-out page in case you have chosen the double opt-out (or Confirmed opt-out) as unsubscription mode (To change this setting, go to Preferences > Properties > Unsubscription).
Use the editor to customize the page and make sure you use the button to get the unsubscription link working.
Please find more information about the different unsubscription methods here.
For a complete overview of the built-in editor, visit this page.
Users, after having clicked on the unsubscribe link, land to a page with the result of the submission ("Thank you! Your information has been successfully updated." Or "Oops! There was an issue. Please try again later." etc).
Use the Options menu on the right to: