www.office.com/setup is the only way to install any of the office 2020 setup on to your system. Use 25 digits unique activation code to redeem your retails card. If you already have used your code then you are all set to download any of the office setup straight from here. While filling credentials of your activation code, you required to log-in first using your registered account. Once you are done, go to cart and from the list of office 365 products download your purchased subscription.