In order to use this theme, you must run a stand-alone installation of Wordpress.
Once you have the zip archive ready, you need to go to your dashboard, which is http://yourwebsite.com/wp-admin and go to Appearance > Themes > Install Themes and, in the top menu, select Upload. Now, select the zip archive and just install it normally.
If the above solution fails due to any reason, upload the theme manually via FTP and then go to Appearance > Themes to enable it manually. If you don't know how to upload the theme via FTP, check Uploading themes via FTP
For further help, you can also read Using themes