I have the keylab and ableton on windows (10) for more than a year, and decided to try once more to set up the transports...
I downloaded the files, did what was in the pdf and it did not work, as reported all over in this thread.
Then i decided to do something weird: in ableton (9.7) in the options/preferences/midi section you have 3 options for your controller;
control surface, input and output. Here I did have the controller and input set, but did not have anything in the output .... (why would i, it is not a synth?).
Setting the output to keylab 61 as well, made the transports work!
It only took me more than a year, but i am happy!
In the second section, midi outputs i also have for the keylab all three options turned on (yellow)
Hope this helps anyone, as i always learn a lot here!