If you connect your computer to the snapmaker through USB you can enter the gcode commands in the console like window on the left. But if you’re asking this question, the chance is very small you would have adjusted these values 
You can also enter the commands over wifi, but then you don’t get the response, just “ok”
You can try again by running the job in the air above your workpiece.
Depending on the material, a 2mm deep cut can be too much for the snapmaker to handle and can be a reason for it to skip steps. (and or break a bit). I usually step down 1mm per pass. Also depends on other parameters.
This thread has a lot of useful info for cnc (and laser): Some info on cnc tool changes and combo cnc/laser projects