To setup the Word Add-in on your Mac you need to have Micrososft Office 2016 version 1701 and above, loaded in your system. Once it's there you can go ahead with the setup which includes following steps:

1. Open a new document in Word.

2. Choose the File tab, and then choose Options.

3. Choose Trust Center, and then choose the Trust Center Settings button.

4. Choose Trusted Add-in Catalogs. In the Catalog Url box, enter the full network path to the shared folder catalog, and then choose Add Catalog.

5. Select the Show in Menu check box, and then choose OK.

6. Close the Office application so your changes will take effect.

7. Too see ICM Word Add-in option on the Word ribbon:

• Select My Add-ins on the Insert tab of the ribbon.
• Choose SHARED FOLDER at the top of the Office Add-ins dialog box.
• Select the name of the add-in and choose OK to insert the add-in