Touch screen laptops can sometimes behave a bit differently from other touch devices. If you are trying to draw with your finger on the screen, you may need to adjust some settings first.
Touch Application settings
The first thing to do is make sure the Magma app has drawing with your finger enabled.
Tap on the Edit menu in your top toolbar;
Sellect Application Settings;
Open the Touch tab and adjust your settings as shown below. One finger drag must be set to Normal;
You might also want to set one finger long-press to None as well otherwise you may accidentally pick colors while drawing.
Disable pressure for the brush
The next thing to do is to disable pressure for your brush, pixel pencil, or eraser tool.
Make sure your layout is in Full mode. Tap the gear icon by the color wheel and select Full mode.
Select your brush tool;
Disable the pressure setting for both Size and Flow. If the button is dark, as shown here for the Size setting, then pressure is currently ON.
You might also want to save this brush as many of the Magma brushes have pressure on by default.
After following these steps, you should be able to draw with your finger on your touch screen laptop.