ikaring

It seems you need to add css rules like so:

.main-navigation.toggled .primary-navigation,
.main-navigation.toggled .nav-menu {
  display: block; }

Have you checked ACF document page?
http://www.advancedcustomfields.com/resources/relationship/

There are some sample codes of relationship field loop.

Ok.
I have found another syntax error.

You need closing } for theme_enqueue_styles.

add_action( 'wp_enqueue_scripts', 'theme_enqueue_styles' );
function theme_enqueue_styles() {
    wp_enqueue_style( 'parent-style', get_template_directory_uri() . '/style.css' );
}

Well, thanks for your proposal, but I dont take any donations here.

PS: I was editing this before your last post. The last one is close, but check below pls.

Not at all.
Follow these steps to modify your child functions.php

1. As @stephencottontail mentioned, you can delete last ?>.
2. Delete these lines:

// This theme uses wp_nav_menu() in two locations.
	register_nav_menus( array(
		'primary' => __( 'Primary Menu', 'twentysixteen' ),
		'topnav'  => __( 'TopNav Links Menu', 'twentysixteen' ),
		'footer' => __( 'Footer Menu', 'twentysixteen' ),
		'social'  => __( 'Social Links Menu', 'twentysixteen' ),
	) );

3. Copy function twentysixteen_setup from functions.php of Twenty Sixteen, they are line 47 -115.

4. Paste it at the end of your child functions.php. (You can hit some RETURN key before pasting for readability. )

5. Modify register_nav_menus section like so:

register_nav_menus( array(
		'primary' => __( 'Primary Menu', 'twentysixteen' ),
		'topnav'  =>  'TopNav Links Menu',
		'footer' => 'Footer Menu',
		'social'  => __( 'Social Links Menu', 'twentysixteen' ),
) );

Now your functions.php should look like this.

<?php
add_action( 'wp_enqueue_scripts', 'theme_enqueue_styles' );
function theme_enqueue_styles() {
    wp_enqueue_style( 'parent-style', get_template_directory_uri() . '/style.css' );
}

function twentysixteen_setup() {
//some code block

register_nav_menus( array(
		'primary' => __( 'Primary Menu', 'twentysixteen' ),
		'topnav'  =>  'TopNav Links Menu',
		'footer' => 'Footer Menu',
		'social'  => __( 'Social Links Menu', 'twentysixteen' ),
) );

//some code block
}

There is a comment on functions.php of Twenty Sixteen.

/**
 * Sets up theme defaults and registers support for various WordPress features.
 *
 * Note that this function is hooked into the after_setup_theme hook, which
 * runs before the init hook. The init hook is too late for some features, such
 * as indicating support for post thumbnails.
 *
 * Create your own twentysixteen_setup() function to override in a child theme.
 *
 * @since Twenty Sixteen 1.0
 */

You can just copy twentysixteen_setup() and paste on functions.php of your child theme, and modify register_nav_menus.

You are welcome.

There seems to exist errors still.
I think there are bad characters in indent.
So try removing indent in the rule set as below:

body .slide-excerpt h2 a {
color: white;
font-family: Georgia, serif;
font-size: 30px;
font-weight: bold;
line-height: 30px;
text-transform: none;
}

Well I dont see the change in your css.
Add “body ” before “.slide-excerpt h2 a”.

Do not touch plugin css, since all customize will be gone when update the plugin.
In order to overwrite plugin css, we are setting high priority css rule set on theme css.

Pls mind that theme css will also be rewritten when updating the theme. That is because we use our own child theme for customizing theme files.