I just connected the garage door to the Homelink and it took me a bit of time. I had forgotten how from my previous car.
I pressed the button on the back of the garage opener. Now I have 30 seconds to connect the car. Press button 1 - hold for 2 seconds - release. Did this 3 times as stated in the manual.
After I completed this, tried the door but no luck. Repeated this 4 or 5 times - still no luck.
Finally, I powered off the car, tried the same thing - and presto - it worked! Apparently, it has to be in OFF mode.