I temporarily solved the libssl problem on my Debian server with the posting of Andargor:
Now I have a new issue when I will start the server about the atlasmanager tool:
I think the SteamAPI error is normal for Linux?! I get the same one on my ARK Clusterservers, but they run without any problems.
Does anyone know what the Signal 11 error mean and how I can solve it? google said its a problem with the memory rights or something like that but... yes, no clue...