Recently I rebuilt an old hand me down laptop which had Microsoft Office installed. I wanted to restore MS Office after the rebuild.
Fortunately I had managed to recover the MS Office license key from the system as a precaution prior to a previous migration from Win 7 to Win 10. That said, the key is of little use without the installation media and the license is for MS Office 2010, which is now an aging product; I wasn't expectant of achieving a successful outcome.
What I found was that Microsoft are still making 2007, 2010 & 2011 for Mac available for download provided you can enter a valid key.
The single image file was just under 700MB, so was available on the laptop in a flash. The installation process wasn't quite so speedy - mostly due to the limitations of the hardware - and did require the product key to be validated a second time.