[Gelöst] Translating website

Background of the issue:
I am trying to translate my website using WPML. The website I need help with is versteckter Link.

Symptoms:
Translations do not work, and the language switcher does not function. I probably can't set it up.

Questions:
How can I fix the translation issues on my website?
What steps should I follow to set up the language switcher correctly?