To set up your account and install Microsoft365.com/setup for the first time, visit Microsoft 365 Setup webpage through Microsoft365.com/setup or office.com/setup before you can install Microsoft 365 or Office 2021 you need to associate it with a Microsoft account, or work or school account. To use Office on your new device, you can activate Office as a 1-month trial of Microsoft 365 Family. You can also buy Office, add Office to an existing Microsoft 365 subscription, or enter a product key from a new product key card. If you have an older copy of Office, you can install that instead.