Too much Travel when installing Mechanical Disk Brake
Without having serviced that exact design, I'd expect that at the very least you'd need to take up the slack in the mechanism. Some slack is to be expected as in similar designs the pads sit back into the housing but pass in through the rotor slot. That means more travel is needed fitting new pads than in operation, easily dealt with by a little preload on the cable. It doesn't surprise me that it's not mentioned, though maybe it would be helpful. Setting the cable position in the pinch bolt with the barrel adjuster wound in is normal for many brake types.
Preloading slightly against a spring also helps keep cable ends nicely seated.