Check the internet connection.
Please check the date and time should be correct on your computer. If not then please correct it.
Now check whether your computer fulfills the system requirement or not to install office setup
now download the office setup from the website office.com/setup
Run the installer,then you get welcome screen. Now click on continue
Now the installation process starts. Wait for couple of minutes to get installation complete.
When office installation gets complete click on Done.