Zotero's newer version, Zotero 5.0 works as a unified application for all browsers. Zotero will automatically detect the operating system in your computer (Mac or Windows) and the browser you are currently using. There are two steps involved in getting Zotero 5.0.
Image represents installing Zotero 5.0 for Firefox in Mac
a). Go to https://www.zotero.org/ and click on the red tab, Download now. Zotero will automatically detect the operating system you use, Windows or Mac.
b). Zotero file will be downloaded to your computer. (Zotero-5.0.4_setup.exe for Windows; Zotero-5.0.4.dmg for Mac). Double click and follow the prompts for completing the installation.
c). Zotero will appear on your desktop.
a). Zotero will recognize the browser you are using (Chrome, Safari, Firefox and Opera). Go to https://www.zotero.org/ and install the Connector for your browser.
b). Click on the link Zotero Connectors for other browsers if you also use other browsers ; select the browser and complete installing the Connector.
c). Follow the prompts to (Allow) complete installing the Connector.
d). The Save to Zotero icon (paper, pdf or a folder) will appear on your browser menu bar.
Windows display the above similar icons in Word 2016