Cannot find Library/Group Containers
I'm trying to manually direct my Word 2016 Startup folder in order to make my Zotero Word plugin appear. The instructions (https://www.zotero.org/support/windows_word_plugin_manual_installation_instructi ons#macword_2016) tell me to direct the Startup folder to something in ~Library/Group Containers/ etc. etc., but I can't find the Group Containers file in my Library folder or ANYWHERE AT ALL. I'm using a mid-2012 Mac running Yosemite 10.10.5. I'd appreciate help either finding my Group Containers folder or figuring out how to get my Zotero plug-in toolbar to appear on my Word 2016.
MacBook Pro, OS X Yosemite (10.10.5)