Zotero Connectors allow you to save to Zotero directly from your web browser with one click.
Connectors are browser extensions, and every browser you use needs a connector installed.
If the button for the Zotero Connector doesn't appear to the right of the address bar in Chrome, it may also appear in the extensions overflow panel, accessed via a puzzle-piece icon. If you find the button in the overflow panel, click to pin it so that it stays visible.
Many institutions require you to sign-in to a proxy system to access library electronic resources while you are off-campus; The Zotero Connector tries to make this more convenient by making it automatic, but for Cornell Library resources, it tends to be more annoying than helpful. You may want to disable it--
Access the Zotero Connector Preferences:
Under "Proxy Settings," unclick "enable proxy redirection"
More info: Zotero Proxy Settings