Replacing Cabin Air Filter

I am looking for help replacing my cabin air filter on my 2002 Ford Windstar. I did not look to see which way the arrow was pointing when I pulled it out and now am not sure whether it should point up or down? Of course all the directions I find say to look at the one you are taking out!

Just a wild guess but doesn’t the arrow show the direction of the air flow?? So it flows from the outside in.