It looks like it's for a specific board. Have you tried dragging it from the 'overlays' button at the top of the icons list to the right, then making it full size, then moving it around? I can't seem to make it work from the usual board overlays positioning when creating the map, but the draggable overlay looks to be working okay. Still, I don't know what board it is supposed to match to. When there are no coordinates, usually it's for a specific board somewhere. [edit -- it looks like it is for a stream board, since the stream area seems to be 'cut out' in the overlay. there are coordinates on the overlay, so that should explain precisely where to put it on the specific board in question]