The author, Kyle Kelly-Yahner, created a hack to send files from feature phones using Twilio and Kloudless. He built upon an existing project called txt.us, which allows sending WhatsApp-like messages, by adding the ability to send files via SMS using a link. The code uses Flask and the Kloudless Python SDK to interact with cloud storage accounts, allowing users to list and download files from their connected accounts. With Twilio's SMS functionality, the author was able to create an app that can send files without requiring a smartphone. The hack is relatively simple, with only about 150 lines of code, making it accessible for developers to build upon and customize further.