*RECOMMENDED*

IMPORTANT: Tech has found a way to by-pass this error with Export Kit installs – and your other Adobe plugins

You can skip the headache of the Adobe solution and manually install or update your CC2015 plugins (quick process): //exportkit.com/answers/install-problem-cc-2015-i-do-not-see-the-extension

From the Adobe Forums (user Spenny):

If you are using Creative Cloud here’s how I got fixed, with help from the Adobe team.

1: Uninstalled all Adobe applications

2: Manual uninstalled any remaining Adobe files, as advised by the Adobe team. The key files are:
Manual Uninstallation of Adobe Creative application
*********
Mac
*********
~ Files / Folders ~
/Applications/Adobe*
/Applications/.AdobePatchFiles (hidden, use Go > Go to Folder command)
/Applications/Utilities/Adobe*
/Library/Application Support/Adobe*
/Library/Application Support/FLEXnet Publisher/
/Library/Preferences/com.adobe*
/Library/Preferences/FLEXnet Publisher/
/Users/[user]/Library/Application Support/Adobe*
/Users/[user]/Library/Caches/Adobe*
/Users/[user]/Library/Caches/com.adobe*
/Users/[user]/Library/Preferences/Adobe*
/Users/[user]/Library/Preferences/com.adobe*

After uninstalling everything I then reinstalled the creative cloud desktop application. Then Adobe DW. and then Adobe Ext manager. When I opened both DW and EM. DW was still not recognised. I closed them went into Creative Cloud.> Preferences.> Logout. When I logged back in Creative Cloud then recognised the installation, run an update for EM. Everything was then up and running OK.