Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hello Laurence Yan Luk
This is most likely a licensing conflict from the previous work account.
Here what you can do:
First, please confirm that your personal Microsoft account shows the Office Home & Student purchase under Services & subscriptions.
Then quit all Office apps, use Microsoft’s Office License Removal Tool for Mac to remove the old work license, reopen Word, and sign in with the personal Microsoft account linked to your purchase.
Also, if Word, Excel, and PowerPoint were installed from the Mac App Store, uninstall them and reinstall Office directly from your Microsoft account instead. Mac App Store versions require a Microsoft 365 subscription and do not support one-time Office Home & Student licenses.
If it still does not activate, please share the exact error message and the year/version of your Office Home & Student license, such as 2016, 2019, 2021, or 2024.
Feel free reply back to this post and update me on this issue, I'll be happy to help.