Add custom field on FluentCart Checkout

FluentCartCustomFieldHooks.php

<?php

add_action('fluent_cart/before_payment_methods', function($args) {

    // Add your field here.....

    // Example Field
    $termsText = 'Yes, I\'d like to receive emails with exclusive offers and updates.';

    ?>
    
    <div class="fct_checkout_marketing_opt_in" role="group" aria-labelledby="marketing_opt_in_label">
        <label for="marketing_opt_in" class="fct_input_label fct_input_label_checkbox">
            <input
                data-fluent-cart-marketing-opt-in="yes"
                type="checkbox"
                class="fct-input fct-input-checkbox"
                id="marketing_opt_in"
                name="marketing_opt_in"
                value="yes"
                aria-label="<?php echo esc_attr($termsText); ?>"
            >

            <?php echo wp_kses_post($termsText); ?>
        </label>
    </div>

    <?php
   
}, 10, 1);

add_filter('fluent_cart/checkout/validate_data', function($errors, $args){
    // Validate data here
    // $args['data']['marketing_opt_in']

    //Example Validation
    if(empty($args['data']['marketing_opt_in'])){
        $errors['marketing_opt_in']['required'] = __('Marketing Opt-in is required', 'fluent-cart');
    }

    return $errors;
}, 10, 2);

add_action('fluent_cart/checkout/prepare_other_data', function($args){
    //Save your data here
    //$args['request_data']['marketing_opt_in']);
}, 10, 1);