Hi candle,
you will need to modify the scene_init.script file to set a different startup position for the actor. You will find this script in the "scr" subdirectory of your scene directory. One of the first few lines says something like:
actor.SkipTo(320, 200);
Change it for example to
actor.SkipTo(320, 500);
Currently your actor is standing within a blocked (non-walkable) area of the scene and that's why Molly cannot walk anywhere.
I will edit the tutorial to make this clear, thanks for pointing that out.