<?php $loop = new WP_Query( array( 'post_type' => 'course_downloads', 'orderby' => 'files', 'order' => 'ASC') ); ?>

$args = array(
    'post_type' => 'course_downloads',
    'meta_key' => 'files',
    'orderby' => 'meta_value_num',
    'order' => 'ASC'
    'tax_query' => array(
        array(
            'taxonomy' => 'people',
            'field'    => 'slug',
            'terms'    => 'files',
        ),
    ),
);
$query = new WP_Query( $args );