Yoast – Custom Taxonomy – primary category

I found this and it works. Shout out to WP Munchies! https://wpmunchies.com/display-primary-category-using-yoasts-make-primary-feature/

<?php
// Fill in your custom taxonomy here
$yourTaxonomy = 'CUSTOM_TAXONOMY';
// SHOW YOAST PRIMARY CATEGORY, OR FIRST CATEGORY
$category = get_the_terms( $postId, $yourTaxonomy );
$useCatLink = true;
// If post has a category assigned.
if ($category){
    $category_display = '';
    $category_link = '';
    if ( class_exists('WPSEO_Primary_Term') )
    {
        // Show the post's 'Primary' category, if this Yoast feature is available, & one is set
        $wpseo_primary_term = new WPSEO_Primary_Term( 'event_cat', get_the_id() );
        $wpseo_primary_term = $wpseo_primary_term->get_primary_term();
        $term = get_term( $wpseo_primary_term );
        if (is_wp_error($term)) { 
            // Default to first category (not Yoast) if an error is returned
            $category_display = $category[0]->name;
            $category_link = get_bloginfo('url') . "https://wordpress.stackexchange.com/" . 'event-category/' . $term->slug;
        } else { 
            // Yoast Primary category
            $category_display = $term->name;
            $category_link = get_term_link( $term->term_id );
        }
    } 
    else {
        // Default, display the first category in WP's list of assigned categories
        $category_display = $category[0]->name;
        $category_link = get_term_link( $category[0]->term_id );
    }
    // Display category
    if ( !empty($category_display) ){
        if ( $useCatLink == true && !empty($category_link) ){
        echo '<span class="post-category">';
        echo '<a href="'.$category_link.'">'.$category_display.'</a>';
        echo '</span>';
        } else {
        echo '<span class="post-category">'.$category_display.'</span>';
        }
    }

}