Once the download finishes, you should close the office.com/setup site along with the browser. Next, follow the steps mentioned down here:

  1. First and foremost, make your way to the newly-downloaded file, which is most likely to save in the Downloads folder.
  2. Once you find the Office installer file, run it by double-clicking on it.
  3. Now quickly read the license agreement for using Microsoft Office.  
  4. Accept it once you have read it.
  5. Next, click the Next button at the bottom.
  6. Continue with the recommended installation method.  
  7. Press the Next option at the bottom.
  8. Hit the Install button.
  9. The installation bar will now start showing the installation progress.
  10. You need to hold on until it reaches 100%.
  11. Close the window by clicking the Finish button.
  12. Reboot your system so that the newly installed program makes necessary changes to your system.  
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