You can download the setup by logging in to your Microsoft account. New users have to create the account by using sign up process. You might be asked to enter the 25-digit product key that you have got with the Office 365 business purchase.In case of any help, call MS Office 365 Setup team 1-888-827-9060 and get an instant solution. You can also call them if an error occurs during the Office setup installation or downloading. The team works for 24*7.