Hi,
What error messages did you get?
Did you have installed other versions of Office before?
I suggest you try to download the tool to uninstall Office from PC completely: https://support.microsoft.com/en-us/office/uninstall-office-automatically-9ad57b43-fa12-859a-9cf0-b694637b3b05
Then re-install Office 2021 again and check if the problem is resolved.
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