If you have already purchased your Microsoft Office 2016 or Office 365 subscriptions and you want to download Office 2016 or Office 365 ISO/IMG files for installation, then then below are links which will assist you.
These downloads come directly from Microsoft servers so there is no need to worry.
These download links can be especially useful if you want to download the Office software once and then install it multiple times.
Download Links for Microsoft Office 365
These links are official links for ISO Image files of Office 365 provided by Microsoft.