You can sign in to Office 365 to download and install Office on your MAC or PC. Here is how to install office 365 on Mac. Go to 'portal.office.com,' and select 'Sign in' if you're not already signed in. Sign in using the account you used to install this version of Office. When logging in, businesses should select 'work account.' If you're using a work or school account, go to the 'Office home page' and click 'Install Office Apps,' then Office 2016. Follow the directions on your computer to finish installing Office once it has been downloaded.