1.) Office Deployment Tool: https://www.microsoft.com/en-us/download/details.aspx?id=49117
2.) Download Configuration File (scroll down to Step Four on this page) - https://www.techsoup.org/support/articles-and-how-tos/how-to-download-and-install-microsoft-office-products-requested-from-techsoup#windows-instructions
For simplicity, use these instructions for your own use after you setup your configuration file:
1. Open CMD prompt from the Windows explorer window where the "OfficeSetup" folder is located (type CMD in address bar). Click in the address bar of where the OfficeSetup folder is located and type CMD, then hit enter.
2. Type this in the cmd line: setup /download configuration.xml (The file will download in the background. You won't notice any change until new line appears in CMD line.)
3. Now, type this in the cmd line whenever it finishes downloading: setup /configure configuration.xml (It will now begin to install. You do not need to enter the license key, as it is already in the installer file.)