Yes, that is correct.
CNC machines, mostly follow a convention that the work area is in negative space. By default grbl (X-carves firmware that lives on the controller) places the work space in negative space.
You can modify grbl so that it works in positive space, however, the way that you tell grbl to work in positive space is that you change one of the compile time options in grbl.
The two .hex files I attached have that compile time option set, so you don’t have to learn how to rebuild grbl.
If you want to use them then you have to upload one of the files to the X-carve controller (works with Arduino and X-controller). you would need to use something like Xloader to update your firmware.
Xloader and instructions can be found here.