This scenario is fairly old and has lots of systems that have been recently implemented that were not present at that time. You will notice RCS does not work... I will update that scenario so at least the RCS works and you can perform a lunar landing. Another thing you will notice is the ECS is not configured at all, another system that was recently implemented.
While you wait for the new scenario, you can just go to the left CB panel in the LM, and hit the RCS - FIRE switch for a few seconds.