By default:
Windows: 7DaysToDie_Data/output_log.txt
Linux: ~/.config/unity3d/The Fun Pimps/7 Days To Die/player.log
Linux with my scripts: /home/sdtd/instances/<name>/logs/current_output.log
MacOS: somewhere in the users profile folder.
Don't ask me whether Tcadmin influences this, I never used it ,)