function check_download( $can, $download, $version ) {

    // Do stuff here

    if ( ! $can ) {

        add_filter( 'dlm_access_denied_redirect', function( $redirect ) use ( &$download ) {

            return wp_fusion()->access->get_redirect( $download->get_id() );

        } );

    }

    return $can;

}

add_filter( 'dlm_can_download', 'check_download', 10, 3 );