Not to validate flat earth, but he's applying North and South to a flat surface which is a compete misreading of that kind of map.

On a flat map of earth, north would be towards the center, while south would be going away from center. So the map doesn't show the sun is setting in north westerly direction. You would have to plot a point on the map and then draw a line to the sun. If the line goes farther away from the center, it would be southernly and if it goes closer to the center, it would be northernly.

Again, not validating flat earth, but this is a pretty gross reading of a flat map of earth, which is pretty common type of projection. Seems like it's called Gnomonic projection.