One important thing you MUST do before you run any trains on the layout you import into Tracklayer/Trainplayer- adjust / align the grid!

The easiest way to learn to do this is to go through at least the first part of the Tracklayer tutorial. It will tell you the method to use in aligning the grid. Once that's done, it will recognize the real size of your layout and give you the right size train images to run on it.