When you click on the SubSim download link for TMO with Training wheels, you should get this:
Which is a Google Drive page. Up in the upper right in the black area, to the left of "Sign In" click box and the 3 periods arranged vertically is the "Download" arrow. It's like an underlined down-arrow. Click on that. You might have to scroll the window in order to see it, if you don't have a bigger screen resolution...