Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Order from Microsoft doesn't come in the format of product key. Your Microsoft account serves as license.
Please go to https://www.office.com
Sign into the Microsoft account you used for the subscription. Click on the 9-dot icon on the upper left > More apps.
Then on the upper right, click on "Install apps". This will now download the installer file. Once downloaded, click on the file to install. It will install the Desktop version of the apps for you then.