A family of Microsoft word processing software products for creating web, email, and print documents.
You Mac is limited to running High Sierra, so the most recent version of Office you can run is 16.43. It sounds like Office didn't get installed correctly.
Unfortunately the Mac version is missing the Repair utility found in the windows version, so you'll have to try repairing by uninstalling and re-installing. To uninstall, please follow the steps on this page: Uninstall Office for Mac Then visitthis page to get a fresh copy of the 16.43 installer (dated November 20, 2020) and run it to reinstall Office. When you first use Word, you'll have to sign in to your Microsoft account to activate your installation.