You have to search for the model in the app, then connect like this, I hope this helps! everything worked for me

The connection to the app takes place after registering and starting it.
I don't remember if it happens automatically or if you have to select the addition of a new device.
Mode A only works after lowering the part that acts as a phone holder and hand grip.
That part has to be lowered all the way to the back of the treadmill.