Updating MS Word for Mac - what should I do to activate it?

You can also get LibreOffice directly from their site:

https://www.libreoffice.org/

Microsoft has a one-time-purchase version of Office (Office Home & Student 2021). It doesn't have all of the features of the Microsoft 365 subscription versions, and I believe that there is an Office Home & Student 2024 in the works. (Which would probably come out the moment you bought the 2021 version.)

https://www.microsoft.com/en-us/microsoft-365/buy/compare-all-microsoft-365-products-b

You can use Web-based versions some of the Microsoft 365 applications for free. Obviously you have to be online the whole time, and I'm guessing these are not as satisfactory as standalone Mac and Windows applications.

https://www.microsoft.com/en-us/microsoft-365/free-office-online-for-the-web

Oldmacuser59 wrote:

... What is the best option for a Mac?

Personally I use Pages, but there are Microsoft Word lookalikes such as LibreOffice as well as other, better alternatives to Microsoft's bloatware:

‎Pages on the Mac App Store

LibreOffice on the Mac App Store

NeoOffice - Office suite for Mac

https://www.libreoffice.org/

These are just a few examples. All are either free or inexpensive and do not require a subscription. What's "best" is up to you, but life is better without Microsoft.

I share Microsoft Word documents with Microsoft Word users all the time. Not a problem. Pages can read and write MS Word formatted documents.

I have had no need for MS for at least a decade and a half.