I am unable to update my Mac so that I can download word. any suggestions?

Your Mac age will determine if you can upgrade to macOS Mojave 10.14.6 or later, the minimum being that version of macOS for installing Microsoft 365 or Office 2019 for Mac.

Using strictly the Safari browser, visit How to get old versions of macOS, check if your Mac meets the hardware requirements for Mojave, and if it does, follow the Mojave link to its download in the Mac App Store. The download of Mojave will be deposited in your /Applications folder.

Always make a Time Machine backup before any operating system upgrade. Check that your printer/scanner drivers are supported by that vendor on the destination operating system.

Details on upgrades to later macOS versions are within article

along with the links to get older downloadable full installers.

• How to get old versions of mac OS - Apple Support

https://support.apple.com/en-us/HT211683

see: Mojave for minimum requirments.

use Safari browser to get all listed installers

• macOS Mojave 10.14 can upgrade High Sierra, Sierra,

El Capitan, Yosemite, Mavericks, Mountain Lion

These compile into working installers and and take time

to be installed and then assemble the new mac system.

• Go64: Check Your Apps and Prepare for a 64-bit World| stclairsoft

https://www.stclairsoft.com/Go64/

Quickly scan your disk for applications, see which ones are 32-bit,

and find upgrade information with the click of a button.

"A fast, free way to get a comprehensive look at your 64-bit app

compatibility & avoid surprises before installing macOS Catalina."

Because Mojave 10.14.6 is the last macOS which supports

both 32-bit and 64-bit software & drivers. Upgrades past

this plateau should be considered; as later macOS won't.