404 after creating a distinct layout for a specific post type (like imprint or data protection)

I just cloned your site and did some tests:

  1. I recommend using lowercase for folder and file names. I don’t know what the Hugo team recommends on this, but this makes it so much easier to manage files and permalinks. So, change legalContent to legalcontent in all the areas it occurs.
  2. You have not defined any permalinks in your config.toml, so Hugo picks your directory and files names as the URL (e.g. example.com/legalcontent/impressum/)