Query for Downloads based on Tax Terms

// WP_Query arguments
$args = array(
	'p'                      => 'download',
	'tax_query'              => array(
		array(
			'taxonomy'         => 'download_category',
			'terms'            => 'oxygen',
			'field'            => 'slug',
			'operator'         => 'IN',
		),
	),
);

// The Query
$query = new WP_Query( $args );