MS Office 2021 license not working on MacBook Air M2.

You can transfer a PC version of Office 2021 from PC to Mac, but you must remove it from the PC, and release it in your account online before it can be installed on another system with the same product key. This is per Microsoft.

In order to release the current install of 2021, login to your MS account online.

Once in your account page, click Subscriptions in the left column. Per my account, I have these two entries.

On your page, you should see an entry for Office 2021. Click the Manage button and choose to release it so it's not in use by any device.

Now you should be able install and activate 2021 on your Mac.

I believe that Owl-53 has put the finger on the problem. If I remember correctly, Microsoft only allows you to install Office Home and Student 2021 on a single Mac or PC. If you have an Office 365 subscription (rental plan), you are allowed to install Office on several of your own computers (Macs and/or PCs) at the same time. This is one way that Microsoft pushes people towards subscriptions.

It does appear that Microsoft might let you transfer your copy of Office 2021 from your Windows laptop to your new Mac, after which you would no longer be able to use it on your Windows laptop.

Microsoft Support – Troubleshoot installing Office

"How do I reinstall Office?

If you're reinstalling Office on a different computer than the one where you originally installed Office, note the following:

• For Office 365 subscriptions: You can install Office on all your devices and sign in to Office on five devices at the same time.
• For a one-time purchase of Office such as Office Home & Business, Office Home & Student, or Office Professional: You can install Office on only 1 PC or Mac. However, you may transfer Office 2021, 2019, or 2016 to another computer that belongs to you if you experience a hardware failure or you buy a new computer. For more information, see the Microsoft License Terms for your product, or see this blog post, Office now transferable."

As for compatibility with Sequoia, there's this:

Microsoft Support – Office 2021 and Office LTSC for Windows and Mac FAQ

"What are the operating system requirements for Office 2021 for Mac?

For Mac users, Office 2021 for Mac is supported on the three most recent versions of macOS. For more information on system requirements, see Microsoft 365 and Office Resources page."

On the linked page, it says "Office for Mac is supported on the three most recent versions of macOS. As new major versions of macOS are made generally available, Microsoft will drop support for the oldest version and support the newest and previous two versions of macOS."

Sequoia is currently one of the "most recent three", and it's been around for a while, so it sounds as if the current Office 2021 for Mac build should support Sequoia – if you can jump through Microsoft's hoops to transfer your copy of Office 2021 from your Windows laptop to your Mac.

Also from an AI / LMM platform

Microsoft Office Home & Student 2021

→ That license is platform-specific.

If you purchased the Windows version, it cannot be activated on macOS.

Since it looks like you will need to decide if you want the expense of an additional Mac-specific license for Office 2021 Home and Student, or switch to free software alternatives, you should know that Microsoft will retire that 2021 suite in Oct 2026. Microsoft applications that you download from the Mac App Store are subscription-based and that requires a different license than the single-purchase solution.

Microsoft does offer a free, web-based Office solution provided you retain a Microsoft account. Read the small print.

If you look at StackSocial, they have a Mac (or Windows) Office 2024 home and business suite going for around $100USD. That is the strategic version of Office for the Mac and what I installed on Tahoe 26.3.

There is the free LIbreOffice Suite which is a deliberate Office clone with reasonably good document compatibility. Ensure you select the Apple Silicon download. LibreOffice also offers detailed PDF documentation of their applications. There will still be a learning curve…

If you want a supported product with Office compatibility, but with a reasonable fee, then there is SoftMaker's Office suite, also deliberately designed to replace MS Office.

what AI says

"Microsoft 365, Office 2024, and Office 2021 for Mac support the three most recent versions of macOS: Sonoma (14), Sequoia (15), and Tahoe (16). Microsoft officially drops support for the oldest major version of macOS as new ones are released, though older software may still run without updates. Native support exists for both Apple Silicon (M1/M2/M3) and Intel-based Macs. Microsoft

 +4

Key Microsoft Office for Mac Versions:

• Current/Supported: Microsoft 365 for Mac, Office 2024, Office 2021.
• Older (Limited/No Updates): Office 2019 (support ended Oct 2025), Office 2016, Office 2011.
• Architecture: Version 16.55 and later provide native support for Apple Silicon. Microsoft
•  +5

Common Supported macOS Versions:

• macOS 15 Sequoia
• macOS 14 Sonoma
• macOS 13 Ventura
• macOS 12 Monterey (often the last supported OS for older versions like 2019). Apple Discussions
•  +3

For the best experience, Microsoft recommends using the latest operating system updates. Microsoft

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ms office mac support versions - Google-

If the earlier replies did not work, contact the Microsoft support team for help. It helps for unusual questions like this licensing issue.

Microsoft's Office now transferable link led to a generic blog page.

I did not see an article there specifically about Office 2021. There was this: Microsoft – Microsoft 365 – Office 2013 now transferable – which is short on detail, but sounds like it applied going forwards.