searching the office 365 installer for Apple OS Catalina 10.15.7

Hello @Frank Overath

As Rayyan mentioned, thank you for the helpful answer, since macOS 10.15 Catalina is quite outdated, if you would like to use a version of the Office suite that is compatible with Catalina, please refer to Update history for Office for Mac - Office release notes. You can use Command + F to search for version 16.66 and download the appropriate build.

Once installed, sign in with your Microsoft account to activate your license. After that, make sure to open Microsoft AutoUpdate and disable automatic updates, as Rayyan suggested.

I hope this information is helpful. If you run into any issues, please feel free to ask

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Hello Frank,

Because Microsoft officially dropped support for macOS 10.15 Catalina back in late 2022, the standard download buttons on the Microsoft 365 dashboard will only try to push the latest incompatible installation packages to your iMac. To get up and running without upgrading your operating system, you need to manually download the final version of the Office suite that was built to run on Catalina, which is version 16.66 (released in October 2022). You can pull this older build directly from Microsoft's official CDN archives by searching for the "Update package for Microsoft 365 / Office 2019" release logs or using the direct package link for build 16.66. Once installed, log into your Microsoft account as usual to activate the license, but make sure to open Microsoft AutoUpdate right away and disable automatic updates so it doesn't try to overwrite the working software with an unsupported version.