Zotero is automatically added to your Google Docs when you add the Zotero browser extension for either Chrome or Firefox (not Safari).
The Zotero Google Docs integration works very similarly to the Microsoft Word add-in.
First steps
Add a citation
Edit a citation
Delete a citation
Add a bibliography
Edit a citation in your bibliography
Before downloading your document from Google Docs when you’re finished, you must Unlink Citations in order for your readers to read the citations as intended.
If you don’t do this step, they just appear as links to the Zotero website.
Troubleshooting
If nothing happens when you click on anything in the Google Doc Zotero menu, hover your mouse over the Zotero icon on your taskbar at the bottom of your screen on a PC, or check your open programs on a Mac. Sometimes the prompt doesn’t pop up on its own. Click on the prompt to bring it up.