Attention Microsoft Word 2016 Mac version 16.xx Users!

There may be a problem with permissions, since EndNote CWYW Word 16.bundle in

/Library/Application Support/Microsoft/Office365/User Content.localized/Startup.localized/Word

had initially 0 bytes (when it is 13.1 Mb)

What  worked for me:

  1. Close EndNote and Word

  2. Go to /Applications/EndNote X8/Cite While You Write and copy  EndNote CWYW Word 16.bundle

  3. Go to  /Library/Application Support/Microsoft/Office365/User Content.localized/Startup.localized/Word and delete any previous copy of CWYW. Then, paste EndNote CWYW Word 16.bundle. You will be asked for your password (it may be the admin password). Afterwards, you see that EndNote CWYW Word 16.bundle has 13.1 Mb as expected

  4. Start word and EndNote