To 3D print, you need to assign the meterial to the extruder in the slicing software (Luban) first. The process of assigning the material to the extruder varies for Single Extrusion Module and Dual Extrusion Module/IEDX, please locate the module you are using and follow the corresponding instructions.
Make sure that the materials assigned in Luban are the same as the one used on the machine. Otherwise, print failure might occur. For example, if the machine is loaded with ABS, but the material set in Luban is PLA, this mismatch can lead to print failure.
Since Dual Extrusion Module/IDEX can use two different materials simultaneously, you need to specify materials for both left and right nozzle.