The new version of Word for the Mac is Word 2016.
The EndNote CWYW plugin does not work with this version of Word.
If you already have Word 2011 on your Mac you can still use Word 2011 with EndNote to CWYW. However, if you have purchased a new Mac with Word 2016 on it, and don’t have Word 2011, the CWYW feature will not work.
Thomas Reuters are aware but as yet there is no date for a resolution to the issue.
See the Thomson Reuters forum at http://community.thomsonreuters.com/t5/EndNote-General/EndNote-for-Word-2016/td-p/124763/page/4