This is what I am greeted with every time any office application is opened. However, Office has already been activated. How do I know? There is another version of Office 2016 that apparently came with this Dell computer. Not Office 365; that would show up under "Programs & Features" in the control panel. This version was under the "Apps & Features" inside of the settings menu, and it was called "Microsoft Office Desktop Apps". I did not notice this was already installed when the company first received the computer. Microsoft Office Standard 2016 was then installed on top of whatever version of Office came with the computer. Upon first installing Standard office 2016 I am able to successfully enter the activation code. However, upon logging in the following day this message appears. Entering an activation code does not seem to work. A yellow message bar appears at the top near the various toolbars claiming that whatever office program I happen to be using isn't activated.
Nothing I've been able to find about changing registry keys worked as the OEM registry key did not exist on this machine.
Since this computer is joined to a domain, I decided to log into another account. Lo and behold, "Microsoft Office Desktop Apps" is listed under Apps & Features. It would seem that this version of Office was never truly uninstalled. I feel certain this issue arises from multiple versions of office installed on the same machine.
I am out of ideas as to what I can possibly do to solve this issue.