Open the Zotero menu in your Google Doc.
The Add Note option will prompt you to sign into your Google account.
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After signing in, your list of Notes will pop up. Click on the note to add it to your Word document. If you have a lot of notes, use the search box (barely visible below the list) to find the note you need.
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If you can't see your list of Notes, check if they are hidden behind other windows.