Change name/path of the file after upload

Hello here,

I would like to change the name and path of my file after i upload it on my wordpress.

I use this filter “wpdm_after_upload_file” in functions.php of my wordpress template but…

I dont understand how to change it…

add_filter('wpdm_after_upload_file',function($filename){
     $filename = 'test.pdf';
     var_dump($filename); 
     return $filename;
          
  }, 1, 10);

var_dump($filename) ►
”
string(8) “test.pdf”
|||name.pdf|||
”

I would like to change the name/path with chosen categories.
Thanks for your help…