This will solve the majority of issues when using Zotero.
If you can't find the Zotero Connector plugin on Chrome:
Click on the puzzle-piece shaped Extension icon in the Chrome toolbar.
Pin the Extension to your toolbar by clicking the Pin icon.
By pinning the Zotero Connector, it will always be available for you to use.
If you are having issues with the Zotero app after it was installed:
If you have used Zotero previously, you may want to consider syncing your library online via a free Zotero.org account prior to uninstalling and reinstalling the app. This will ensure that you don't lose the items that were already available in your library.