Here's what they said to us via their support system:
With this response, we believe your issue is resolved and have therefore closed your case 0187952134. If your support case has not been completed to your satisfaction or you need to contact us on this issue again, please reference your case number.
Thank you for contacting Adobe Technical Support. This email is with regards to that you are unable to find Extract option on creative cloud site.
Extract for Creative Cloud Assets Online Service and Brackets is discontinued with effect from June 28th 2016.
You can access this feature now within Photoshop and Dreamweaver ( via Export assets panel ) software.