To Install purchased office 365, go to office.com/setup and sign in with the Microsoft account used during purchase. From your dashboard, click Install Office, follow the prompts, and start using your apps right away.
Steps to Install purchased Office 365
 
  1. Visit office.com/setup.
  2. Sign in with your Microsoft account.
  3. Go to Services & Subscriptions.
  4. Locate your Office 365 product.
  5. Click Install Office Setup.
  6. Download the installer.
  7. Run the setup file.
  8. Follow installation instructions.
  9. Launch any Office app.
  10. Sign in to activate and start using Office 365.