You will use your Microsoft account for everything you do with Office .
office.com/setup If you use a Microsoft service, such as Outlook.com, OneDrive, Xbox Live, or Skype, you already have an account.
office.com/setup Office Setup is use for installing application software Microsoft Office.
office.com/setup This application provides you a chance to work on Word, Excel,
office.com/setup viewpoint, onedrive.Log in with Microsoft Account using Id and password associated
office.com/setup with the copy of MS office you have bought | Setup Office 365/2019.