Instead of taking out the guards to the left, get spotted before Hans has a chance to get himself shot, bleeding out, and putting a timer on the mission.
You can’t open most of the doors, but the bandits can, so keep that in mind if you want to explore the entire castle. Toth isn’t there though, and neither are the hostages.
After killing all the bandits, and taking the castle, you can go back to the ladder, and you can have a conversation with Hans about how you didn’t do too well. The game continues as normal.