Is a new Microsoft Office 2021 purchase required for compatibility with macOS Sequoia?

No, if you already have the 2021 version then it should still work, you don't need to buy a new license for it.

What do you mena exactly by "stopped working"?

Can you not open the apps? You may just need to update them from the App Store app.

There is a known glitch with the recents view and the app's direct access to the files which prompts for granting access and may prevent opening the files. This is usually resolved by opening the file directly from Finder instead of using the Office Apps's recents view.

Microsoft supports Office 2021 for Mac home & student on macOS Sequoia, Sonoma, and Ventura only for new, or existing installations. So that Microsoft information is partially correct. Your Office 2021 for Mac should not have stopped working on Sequoia. My installation of Office 2021 for Mac did not stop working on Sequoia.

What did you install or remove before Office ceased working?

You will likely need to contact Microsoft for support.

Unrelated to Microsoft Office, there is a Sequoia v15.3.2 update available in System Settings > General > Software Update and it would be good to stay current.

If I had to guess it sounds like Microsoft has made some changes regarding compatibility between Microsoft Office Home & Student 2021 and macOS Sequoia. The statement you found suggests that only new single-purchase installations of Office 2021 are supported on Sequoia, which implies that previously installed copies might not work after the update.

Some things you can try:

• Verify Your License – Go to Microsoft Account > Services & Subscriptions to check if your Office 2021 licenses is still valid. If they are, then try both of the following:
  • Open any existing Office app on your Mac > Click Help > Check for Updates (via Microsoft AutoUpdate) to see if it will allow you to update your current installation.
  • Try downloading the latest installer from the Microsoft website and sign in with your Microsoft account.
• If is not, and you don't want to purchase new licenses, consider using a free Office alternative. These are:
  • Microsoft 365 Online
  • LIbreOffice
  • macOS Pages, Numbers, & Keynote

You can also contact Microsoft directly to see what options are available to you.

Do you see a tan banner at the top that says "Subscription required to Edit and Save..."

If so, either you somehow are using the Office 365 applications which require a subscription, or your home and office installation lost its activation.

If you click on the banner at the top it should prompt you to sign in with your Microsoft account that is tied to that purchase.

renee626 wrote:

Can you please clarify "update them from the App Store app"? Is that Apple App Store app? or Microsoft App Store app? I am not a fan of Microsoft so I don't even know if that is a thing... or where to find it)?

Updates to the Stand alone releases should happen directly through Microsoft Office. Not the App Store. That's only used for the Office 365 subscription versions.

Also, there is no Microsoft App Store for Macs.

renee626 wrote:

Not sure what 365 Online is but I am NOT a Microsoft fan so if it is any kind of subscription that will be a hard no for me.

FYI ... The Microsoft 365 online version (also known as Microsoft 365 for the web) requires a Microsoft account, but not a paid Microsoft 365 subscription.

You can use web-based versions of Word, Excel, PowerPoint, Outlook, and other apps for free at office.com. However, these are limited in features compared to desktop versions.

Anyone with a Microsoft account (e.g., Outlook, Hotmail, Xbox) can sign in and access the online apps. Files are saved in OneDrive, which comes with 5GB of free storage.

I use word and powerpoint almost exclusively and learning something new of converting a ton of files to something new shoulds like a nightmare.....

The other free alternatives, I have already mentioned, can read & write Office documents.