If you bought Office setup License from a physical or an online store, you must have received it in the form of a product key. Office com setup can be directly activated by the product key. But it is best recommended to link the product key with your account first and then Sign In with the same account. To do so, you can follow these steps. Make sure you have the product key ready with you.

Go to office.com/setup. Sign in using your Microsoft account, Now enter the 25-character long product key as mentioned, Select your country and your language. Click on Next, After this, you will be redirected to MS office Services and Subscriptions Page, Locate the product you just activated and click on Install Now to download the setup, Run the setup to install Office Setup on your computer, When prompted, Sign In using same MS Office setup Account.