Open Prusaslicer and import attached configfile. (Not mine, made by Rainer)
Import both .STL files, at the prompt, select multicolor.
print :)
More info about multicolor printing:
https://forum.prusaprinters.org/forum/prusaslicer/manual-multicolor/
https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-how-do-i-print-this-printing-help/acting-as-my-own-mmu
The author hasn't provided the model origin yet.