On the confirmation pop-up, click on Yes to Run the problematic Microsoft Office Program as Admin.
Type Name of the Microsoft Office program in Search bar > right-click on the Office Program in search results and click on Run as Administrator option. To fix this, simply try to run any Microsoft Office program (Word, Excel, Power Point) as Administrator.
It is possible that Microsoft Office is not being activated on your computer due to permission issues. So, let us go ahead and take a look at some of the methods that are known to fix Microsoft Office Activation errors on a Windows computer. This problem can also occur if you are trying to activate Office 365 on a computer on which an older version of Microsoft Office was previously installed.