As a mission, i have to enter the monastery.
But after talking to “Carl” nothing happens. No further conversation with Carl is possible.
What am i missing?
Wait until Karl goes to sleep, he’s in the room farthest down when you go up the stairs. Unlock the chest and grab the writ
I have same problem. Plus i thought i need his clothes so i killed him and took his clothes… wasnt worth it… i dont know what to do now 
… you only need the letter, hope you picked it up from his body …
with that letter go to the guy who is left from the main entrance up the stairs and show him the letter …
grab your clothes …
(HINT store ALL your things in the tavern after you bought the room there …
also enter the monastery early in the morning, so you have one day to feel home in the monastery … read the book they gave you careful and do your tasks … )
I transferred all my posesions to my horse…hope it’s still there afterwards… 
It’s really not hard. Read the quests. It tells you what to do, and if it doesn’t you use common sense. If it says wait till someone goes to bed, you don’t kill them.