NOTE 1: The Zotero toolbar does NOT work with Office 365 (Word Online) or Chromebooks.
NOTE 2: The Zotero tool does work with MS Office (software) and Libre Office, a free software office suite for Windows, Macs, and Linux.
NOTE 3: The Zotero toolbar in Word (software) may use the term "Zotero", "Add-in" or on Macs an icon (looks like a whistle).
The following video shows how to integrate in text citations from your Zotero library and create a bibliography from each citation you have used in your text:
The presenter of the above video uses the Classic view when making a selection to cite a reference. "Classic View" is not the default option when you download Zotero, but it is a useful option to set up as your preferences:
The follow video shows how to change the existing referencey style of your document to another: