Under Authentication, select Token. Authenticate using your UTLN and encryption password (usually the same as your Tufts password)
If Token authentication fails you must authenticate using a recovery File.
To obtain the recovery file, in ePO Console, select the system you are trying to Decrypt under System Tree
Actions> Drive Encryption> Export Recovery File Information, OK (If you don't have option for Drive Encryption, your account does not have privileges to export recovery keys. Please contact support-systems@email@example.com).
Place exported XML file on a USB memory stick. Authenticate using this file (under Authentication select File, and browse to XML).