This is the Microsoft downloader exe use the product key here in the description 
I don't know how long this will last but give it a try.

Use the product key provided below to activate your trial.

Product key for the Office 2016 Preview
NKGG6-WBPCC-HXWMY-6DQGJ-CPQVG


Once the trial period expires, you will have the option to purchase an Office 365 subscription or reinstall your current version using your original product key, learn more