HTTP Error 500

I have installed and activated free Total theme from
https://wordpress.org/themes/total/
There is not errors on me dev site.

Check your configuration
1.
Usually 500 Internal Server Error is connected with wrong Apache configuration
(missing module that is mentioned in htaccess or something like this).
Check your error.log right after the error occurs for details.
2.
The script tries to get more memory than is limited by the ‘memory_limit’ parameter.

There is the fast fix for v.1.1.8.
File
wp-content\themes\total\inc\customizer.php
You can insert

if ( ! class_exists('WP_Customize_Section') ) {
	require_once( ABSPATH . WPINC . '/class-wp-customize-section.php' );
}

before

/**
 * Pro customizer section.
 *
 * @since  1.0.0
 * @access public
 */
class Total_Customize_Section_Pro extends WP_Customize_Section {