You can find all the information on sofi.com. Here's the direct link https://www.sofi.com/money/mastercard-benefits/.
Once there, click on the 'View all Mastercard benefits' link, and the 'Mastercard® Guide to Benefits' PDF will populate. 
Scroll down the page to the 'Mastercard ID Theft Protection™' section which includes general information and how to file for coverage.
