Zotero is the best choice for Mac users. It also plays nicely with PC's.
At https://www.Zotero.org/download/, click to download BOTH Zotero AND the Zotero Connector. You need both tools, working together:
In ONESearch, click on Export .RIS to save the file:
Click the green button to download:
When you click on the file, it should automatically open Zotero and dump in your citation for you.
To export a citation from Google Scholar or another website to Zotero, click the button in the far right corner of your browser (circled here):
Within Word, to add a citation or Bibliography, click the Zotero button, and you can choose how to proceed: