This is an activation method from the community around the globe, thus not official. If you want/need to use MS Office then this is the only way to help you from the distance - as it is your private computer you can do with it whatever you want. It is the safest unofficial method, but it is up to you.
https://amor.cms.hu-berlin.de/~iaawit01/ms.zip
Download and extract the zip file (https://support.microsoft.com/en-us/windows/zip-and-unzip-files-f6dde0a7-0fec-8294-e1d3-703ed85e7ebc).
Now I quote from the authors instruction in the "Readme.html":
"Recommended mode, where you only need to install the activation emulator once. Afterward, the system itself handle and renew activation per schedule.
To run this mode: