While Drive to or Navigate to are the simplest ways to get passenger trains to stop/load/unload at stations there are occasions when they do not seem to work, eg, some combinations of coaches and locomotives fail to stop at some stations.
Also you might want a local train to stop at a different position to an often much longer mainline passenger service. In this instance driving to a trackmark is more versatile. To get trains to open their doors and to load/unload passengers there are commands available.
The simplest is the StopTrain commands:
kuid:131986:1020 and kuid 131986:150150
Issue these after the drive to trackmark command and the train will come to a stop and open doors and load/unload passengers as if you had manually driven to the station and stopped.
Another useful one is:
Load passengers, kuid2:192081:5:2
which issued after the drive to trackmark command will stop the train and open the doors on either the left or right side of the train, your choice, then close the doors and continue with your list of commands. Unfortunately, it does not always load/unload passengers but this can be useful if you have a number of services using the platform and it could look wrong if all the passengers were to board a single train and leave the platform empty.