action hook

Hi!

I want to customize the content of the wrapper on the post grid loop this way:
https://pickplugins.com/documentation/post-grid/action-hooks/post_grid_item_bottom/
I added the code to the functions.php of my child theme or as as a new plugin but I can't make it work. It doesn't happen anything.

I can't find the action hook "post_grid_item_bottom" in the plugin files either.
Are the instructions up-to-date?

The grid ist on this page (combination with serach and filter pro):
https://autohausbuendgen.webatelier.org/eu-neuwagen/eu-neuwagen-im-haus/
Thanks you very much for your help.

Nathalie
(by the way the search function of the forum doesn't work. I don't find any results even if there are some items with the search terms).