The download of Zotero should automatically install Zotero within Word, in a connection similar to those used in EndNote.
A tab for Zotero appears at the top of the Word screen: within this are options for in-text citations and bibliographies.
The Document preferences function is to change referencing styles as required.
Citation and bibliography details below,
See also the Zotero support page on Using the Zotero Word plugin.
Add / edit citation from Zotero in Word.
1. Choose the citation style and then 'OK' at the bottom
2. A red search bar should appear on-screen.
In the pop-up which shows your Zotero folders:
In Word, using the Zotero tab at the top of the screen.
Once you have completed your document, or earlier if you wish to check this function:
If you need to change the referencing style: