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If you are using a Mac you will need to have the most a recent version of Microsoft Word for Mac (2016 or higher). The previous versions for Mac do not have the Accessibility Checker. Maybe that is part of the issue. To find out what version you have, go to the top menu, look for Word, then About, then within that modal look for Version—you want it to start with 16 e.g. 16.4.3 or "License," which should have the year 2016 or later.
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Looks like I don't have the right version. How do I upgrade?
It is pretty easy. Go to the KnowledgeBase Software Installers page and look for Microsoft Office 2019. You can also go directly to Visit the Microsoft Office 2019 download page. Follow the directions there, and if you run into any issues with the installation, contact the ITS Help Desk.