I succesfully loaded other projects in it, but this one seems difficult. I am currently trying out Twinmotion and I have to say that the direct linking is not really reliable at this moment.
You seem to have made the Datasmith connection to your Archicad scene which is great. Now all you need to do is be on the 3D view inside of Archicad and press the Sync button on the Datasmith toolbar, or turn on Auto-Sync, then click back into your Twinmotion scene and that geometry should come through.