Intially you have to create or load a game once after first startup. After that the Autoload Mod jump starts into the previously loaded savegame everytime you rerun the container. You can also edit the config file of the Autoload Mod to archieve similar behaviour.
The game, the modloader (SMAPI), and the "Always On" Mod is pulled from my servers to minimize version conflicts. Afterwards everything will be unpacked into the right places. In the end of the init script the game will be started inside Xvfb.
Usually you should be able to ignore any messages. If the game doesn't start or any errors appear, you should look for message like "cannot open display", whiich would indicate most likely permission errors.
### VNC
Access the game via VNC to initially load or start a pregenerated savegame. You can control the Server from there or edit the config.json files in the configs folder