You can use Zotero to write citations for you in Microsoft Word by using the Zotero Word Plugin. There are also plugins available for LibreOffice and Google Docs, but this page focuses on Word.
The Microsoft Word "add-in" may already be installed when you install Zotero 7.0. To check this, and install the "add-in" if necessary, go to Zotero settings. Then click the "Cite" link on the right (see screenshot below).
As with any automated citation creator, Zotero is bound to make some mistakes in your citations and bibliography. Furthermore, you may want to change some of the citation formatting to suit your needs. Follow the instructions here to make sure your changes are not unintentionally reversed!
If you see issues with the information in the citations (titles, author names, etc.) including capitalization errors, the best way to fix these is to correct the information in your Zotero library.
Many citation styles will require you to add additional text to your citations, especially if you are using footnotes. You may also want to change the order in which Zotero lists citations within a note, or other such tweaks. Zotero does allow you to customize your citations by adding page numbers, prefixes and suffixes. However, this functionality can be tedious in some citation styles. You can type directly in the Word document to change a citation, but you must first unlink your citations, or else your changes will be lost when the document refreshes.
When you are sure that you have added all your citations to your document, that you have added your bibliography/works cited section, and that all incorrect citation information has been corrected in your library, refresh one last time. Then, you should unlink the citations from Zotero by clicking Unlink Citations in the Zotero menu. This will turn all the citations into normal text and prevent Zotero from changing anything without your knowledge. At this point, you can proceed to edit your document like a typical Word document.