I would guess that you either need to speak to another Focus owner that flat tows or a Ford Tech online.
As a “swag” I’d expect to get that notice any time I turned off the car when not in park. But understand the need to have confirmation from someone that knows.
My Lincoln sets up and works differently, and chimes a unique chime when it’s ready to tow and it shows a message that it’s ready to tow, but the info center still tells me to put my foot on the brake to start the car. Which obviously I don’t want to do so I ignore that message. After turning off the car there are no more messages on my car.
You might try posting this question on www.irv2.com
it is much larger and covers all brands but would have a greater number of Ford Focus owners that would have experience with the process.