Microsoft word for macOS Sierra Version 10.12.6

There is no longer a version of MS Office available that will run on Sierra.

Look into an alternate office suite.

Microsoft only supports the last three macOS versions for new Office installation, and that means the current 64-bit Microsoft 365, Office 2019 for Mac, or Office 2021 for Mac with the oldest operating system (currently) being Catalina. All earlier versions of Office have been retired and their license servers disabled.

Consider trialing SoftMaker's Office 2021 for Mac which is still supported on High Sierra, or for a longer learning curve, there is the free LibreOffice Suite, also an MS Office clone, and still supported on High Sierra — until Feb 2023 when it will require Mojave for new installations.