I've used ES2, and then upgraded to ES3; and then to ES4. All that stuff's missing now. HELP!
Designer has been debundled from Acrobat since version XI and was replaced with the already discontinued FormsCentral.
Acrobat DC now includes neither Designer nor FormsCentral, but Designer ES4 is available as Stand-alone application in Adobe's store.
If your Designer was bundeld to a previous Acrobat (8, 9 or X Pro) it has been removed during installation of DC I'm afraid.
But, if you have a saparate license for any of the previous versions, you can in install parallel to Acrobat DC to make Designer available again.