You may be asked to submit a Word manuscript without bibliographic metadata or formatting. Some may even state: “Please do not use reference management software in your Word document (e.g. Zotero, EndNote or other referencing system.” What is being asked is that you submit a final manuscript or document without the embeded Zotero field codes.
When you are done citing using Zotero, make a copy of the document and use "Unlink Citations" to flatten all Zotero citations into plain text. Look over the citations and bibliography entries to ensure that they're correct.
Warning: Unlink Zotero citations in the document remove the field codes. This prevents any further automatic updates of the citations and bibliographies. Note that removing field codes is irreversible, and should usually only be done in a final copy of your document.