The 4.2 meters are a theoretical maximum. It's like I would say this car drives 180mph - of course it depends on the terrain if you will be able to gain that speed or not and that is also with the pump. It depends one a few things, mainly the resistance in your loop. If there is a low resistance you will reach a lower frequency as the maximum and on the other site you can reach a much higher frequency if also the resistance is very high. Reaching 100Hz is almost impossible. Everything beyond 90Hz is already an exception and would mean that your loop is very restrictive.

Because of the dynamic frequency adaptation there is also no way to say if you can reach the 4.2m and if so at which frequency. We did a measurement where the pump had to push against a sensor and ended up with that 4.2 meters.

As default the pump runs in an automatic mode where it automatically detects the highest possible frequency itself. Of course you can also change all settings in the software and store them into the pump. So even without USB it would run with the settings that you have done before.