Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hello Sylvia,
Welcome to the Microsoft Community.
We understand you want to continue use Microsoft Office products. Please understand that Microsoft 365 is basically a paid service, and you'll need a subscription to use the full features of it. Free Trial - Try Microsoft 365 for a month - Microsoft Store
You can visit the Service and Subscriptions page to find your paid Office subscriptions or one-time purchases. Unfortunately, I guess you may not be able to download and use Office Home and Business 2016 on your Mac, because it's a too earlier version of Office product, and does not support the latest MacOS for now.
While the desktop Microsoft 365 provides the complete Office user experience, you can use office.com to get the most basic Office features for free online.
Thanks for your understanding and support. Should any uncertainties arise subsequently, please feel free to seek assistance once again.
Best Regards,
William.Y | Microsoft Community Support Specialist