I believe you are trying to do something that is not possible.
The custom redirection URL is for cases where there is a working custom permalink scheme for search results, and you want the plugin to adapt to it as well. It is simply impossible to redirect (or in this case push) the results to a custom page. The search query results are always handled by the search.php file in the theme directory, when it is invoked.
It is possible to change the default search URL scheme with custom code, for example this tutorial explains 2 possible ways: https://wordpress.stackexchange.com/questions/54832/wordpress-custom-search-url
These solutions only create a ‘mask’ for the WordPress to resolve and properly call the search results template file. This will not change the layout of the results page – that is completely controlled by the theme.
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