Trouble with theme "arthemia"

Hi everyone,

it does not show any pictures or thumbnails on the front page. I have no clue what to do, I think it might have to do with the script for automatic resize of images that came with the theme. Here is my website:

https://www.phucsteufelswild.de

Please help me get that fixed. I did everything written in the FAQ here:
https://michaelhutagalung.com/2008/05/arthemia-magazine-blog-wordpress-theme-released/

I changed the directories scripts and cache to 777. And when I add a custom field, I choose image, then the url to the image starting with wp-content as described.

Any help would be kindly appreciated.