orcaslicer allows you to add filaments needed for a print and paint your model with them, and the snapmaker fork simply picks the closest match of the colors and materials you've chosen to the ones it has loaded. you don't really need to care about which extruder has what, as long as you set the right type of filament on the printer. and if you use rfid spools that's also automatic. you can of course override that in the slicer if it selects the wrong filament.

the easiest way to start with is to simply fetch the loaded filaments from the printer and use those. when snapmaker orca is connected to the printer you get a "loaded filaments" section in the selection dropdown.