Important
This never worked well and there are much better solutions out there. I would recommend taking a look at Konnected Garage Door Openers, which support Hubitat, Home Assistant, Control4 and other cloud based home automation platforms.
This project contains the Raspberry Pi and Hubitat driver code for a Raspberry Pi hat for controlling a garage door through Hubitat. The hardware includes a relay for actuating the garage door controller, 2 door sensor inputs (open/closed), and status LEDs to communicate door status.
See the project wiki to get started.