Hello @TNH,
please make sure that you're playing a pre-defined scenario from the "Standard" tab at the top when starting the game. Playing a quick scenario is nice. However, it usually does not give you the red bar you're talking about. (And it may tell you at the end that the scenario was not completed successfully)
Though, you can still "complete" the scenarios within a quick game. It just tells you that the scenario was not completed, AI trains do not open the doors and AI trains have no train destination indicator on the train itself.
Additionally, I would highly recommend using the manual door controls since you can then decide for yourself when you want to close the doors. The automatic door controls close the doors automatically, and the "T" button (keyboard shortcut i) doesn't do anything.