Kmonad configuration to type german special characters?

Hello everyone, I am currently trying to set up a kmonad config file to replace the autohotkey script I used on windows. My goal is simply to use the right alt key in combination with a,o,u and so on to type german umlaut characters like ä,ö,ü, etc.

So far I am having trouble even getting kmonad to run the config. I guess I probably misunderstand how this is supposed to work significantly. My initial config file was generated by ChatGPT since I had no idea where to even start.

This is my current config file

    
(defcfg
  input  (device-file "/dev/input/by-path/platform-i8042-serio-0-event-kbd")
  output (uinput-sink "kmonad_keyboard")
  fallthrough true
  allow-cmd true
)

(defsrc
  ralt a o u s lsft
)

(deflayer german
  ralt-a "ä"
  ralt-o "ö"
  ralt-u "ü"
  ralt-s "ß"
  ralt-shift-a "Ä"
  ralt-shift-o "Ö"
  ralt-shift-u "Ü"
)

  

Any help would be appreciated.