Neil,
Going out on a limb here / complete guess, but maybe it's that you need to go into Open Rails and manually add the dummy folder as a new installation profile under the Content tab (which I'm not sure will work with the absence of the pertinent subfolders ROUTES, GLOBAL, SOUND, and TRAINS and having some real route or trains content inside them). Again, just a guess
I won't make any plugs for the quality of the route itself since I am biased (for obvious reasons haha) but I will note that a SIGNIFICANT part of the value of the expansion pack is the approx. 40 hours worth of new activities for Mullan that makes use of the new content. I feel pretty confidently that these are some of the best activities that we (TS) have ever made.