Unable to install Microsoft 365 on macOS Big Sur – need Office 2019 download

Question

I have an older MacBook Air running macOS Big Sur. I currently have a Microsoft 365 subscription, but I’m unable to install its applications due to the age of my device. As an alternative, I plan to install Office 2019 and link my subscription to that version. Therefore, I need to be able to download Office 2019.

Answer 1

Office 2019 can be installed and then activated with an eligible Microsoft account, but it cannot be activated using the Microsoft 365 subscription license itself. Microsoft 365 and Office 2019 use different licensing: the Mac App Store and current Microsoft 365 installers are not compatible with Office 2019 licenses, and vice versa.

To use Office on an older macOS version like Big Sur when the current Microsoft 365 installer will not run, the supported approach is to install an older Office build that still runs on that macOS version and then sign in with the existing Microsoft 365 subscription to activate it. Moderator guidance in similar scenarios (Ventura, Monterey, and other older macOS versions) is to:

1. Install the most recent Office version that is supported on that specific macOS release (an older build of Microsoft 365/Office for Mac).
2. Activate it by signing in with the Microsoft 365 subscription account.

For Big Sur, follow the same pattern as in the referenced Q&A posts for Ventura and Monterey: obtain the most recent Office build that runs on Big Sur and then sign in with the Microsoft 365 subscription to activate it. The referenced “Most Recent Office You Can Run – Best Practices” guidance (mentioned in multiple moderator answers) is the documented path for downloading and activating the correct older Office build for an older Mac.

If the goal is specifically “Office 2019” as a perpetual (one‑time purchase) product, that requires a separate Office 2019 license associated with a Microsoft account; the Microsoft 365 subscription cannot be converted into or used as an Office 2019 perpetual license.

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References:

• Microsoft Office and the Mac App Store
• Download and install or reinstall Office 2021, Office 2019, or Office 2016
• What to try if you can't install or activate Office for Mac
• Troubleshoot installing Office
• Download, install, or reinstall Microsoft 365 or Office 2024 on a PC or Mac
• How to download Microsoft office (not 365) to MacOS Venture 13.7.8 - Microsoft Q&A
• Help! I can't get 365 to work. Can I use it on my MacOS or do I need Office? - Microsoft Q&A
• Office running on OS 12.7.6 - Microsoft Q&A
• Cannot install Microsoft 365 because my os is too old - Microsoft Q&A