Hello,
i want to import post from a non wordpress to a wordpress page,
i do it with wp_insert_post() but how can i import images and fill the acf-image-fields in my post?
You need to
1) Insert the image into the media library https://codex.wordpress.org/Function_Reference/wp_insert_attachment
2) Use update field (using the field key) and the ID returned from step 1 to add the image to the acf image field.