I even noticed that the Firefox add-on that was promised with the stand-alone install, never happened.
A Unified Zotero Experience The two full versions of Zotero, Zotero for Firefox and Zotero Standalone have been replaced by a single standalone application for users of all browsers. A new Zotero Connector for Firefox, similar to the extensions available for Chrome and Safari, allows you to save to the Zotero desktop application or zotero.org in a single click. If you're a current Zotero for Firefox user, you'll be automatically upgraded to the Zotero Connector for Firefox, and you should install the Zotero application if you don't have it already. Blog post forthcoming with additional details
I thought it would prompt me when I installed the stand alone.