Thanks for the info.
LiftMaster Model 882LM Multi-Function Control Panel is Security+2.0. There’s a paragraph about it in the installation instructions under “Wiring Research”.
Connecting Garadget directly to the opener doesn’t work because the the openers enabled with Security+ 2.0 (MyQ and AssureLink models from LiftMaster, Chamberlain and Sears) can’t be triggered with a toggle. They must use the encrypted serial protocol supported by remotes like the 882LM.
Wiring Garadget to the button pads of a spare wireless remote or wall remote are the valid solutions for this. Essentially Garadget’s relay will be pressing the remote control’s button for you.