When I export at 300ppi my dimensions export much bigger?

I'm simply trying to export a t-shirt design at 3600 x 3000px (300ppi) as a png for printing but everytime I do the file comes out 11936 x 8765px and is way too big. Surely there's a simple way to do this in illustrator especially when there are apps like kittl that has no problems and is very simplistic just type, click and done. Can anyone help please because I'm beyond frustrated at this point.

Thanks in advance.