Add supports to the pegs, otherwise print it upright. 15% infill, 0.3 mm layer height. I added brims because I was having issues keeping the supports stable, but your mileage may vary depending on your slicer settings.
The author remixed this model.
Merged two 2-slot boxes andt then added parts to fill the boxes then subtracted cylindrical shapes using Orca slicer. Would likely do a better job using CAD but I am still learning.