Okay. So any CPT created in WordPress has their permalink prepended with the CPT slug so your single page should be /dier/felix, not /felix. /dier should load your archive.php file in the theme and loop out all the posts ordered by date (provided archive.php has a regular loop).
I think you might have a permalink clash somewhere. Do you have a page with a slug of pier as well? That usually causes issues.
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users