Full conversion help!

[Kounumbra]

That can only mean the launch option cannot find the main_init.cfg file. Remember, it should be a relative path to the config, starting from the Amnesia root folder. So to start the normal game with the use of this path, it would be config/main_init.cfg.

White Night uses its own config folder in the root, so that one's path would be wn_config/main_init.cfg. If you have an isolated mod, it will likely be within another level, like modname/config/main_init.cfg.

What mod are you trying to install?

Just White Night at the moment.