Ok, I was getting an error log every time someone loaded the product write review page, even if they didn't write a review.
So I decided to undo the change I did and install this plugin.
I'm running fresh install of Zen Cart 1.5.7c on PHP 7.4.22 with OPC and IH5 Installed.
It works, guest can leave reviews and their name appears, thank you.
I am however getting Error Logs with this
I know you said this hasn't been updated yet, but is there a way you can help resolve some of these errors in the log if it's not too much trouble, or if anyone else with the skills to help!? (I've added the corresponding php line under each php notice!)
Thank you in advance.

Code:
Request URI: /01/index.php?main_page=product_reviews_write&products_id=47&cPath=1
#1  require_once(/01/includes/languages/english/responsive_classic/product_reviews_write.php) called at [/01/includes/modules/require_languages.php:22]
#2  require(/01/includes/modules/require_languages.php) called at [/01/includes/modules/pages/product_reviews_write/header_php.php:18]
#3  require(/01/includes/modules/pages/product_reviews_write/header_php.php) called at [/01/index.php:35]
--> PHP Notice: Undefined index: customer_id in /01/includes/languages/english/responsive_classic/product_reviews_write.php on line 13.
if( $_SESSION['customer_id'] ) {

Request URI: /01/index.php?main_page=product_reviews_write&products_id=47&cPath=1
#1  require(/01/includes/modules/pages/product_reviews_write/header_php.php) called at [/01/index.php:35]
--> PHP Notice: Undefined index: customer_id in /01/includes/modules/pages/product_reviews_write/header_php.php on line 42.
    if (!$_SESSION['customer_id']) {

Request URI: /01/index.php?main_page=product_reviews_write&products_id=47&cPath=1
#1  require(/01/includes/templates/responsive_classic/templates/tpl_product_reviews_write_default.php) called at [/01/includes/templates/responsive_classic/common/tpl_main_page.php:178]
#2  require(/01/includes/templates/responsive_classic/common/tpl_main_page.php) called at [/01/index.php:94]
--> PHP Notice: Undefined index: customer_id in /01/includes/templates/responsive_classic/templates/tpl_product_reviews_write_default.php on line 16.
    <?php echo zen_draw_form('product_reviews_write', zen_href_link(FILENAME_PRODUCT_REVIEWS_WRITE, 'action=process&products_id=' . $_GET['products_id'], ($_SESSION['customer_id']) ? 'SSL' : 'NONSSL'), 'post', 'onsubmit="return checkForm(product_reviews_write);"'); ?>

Request URI: /01/index.php?main_page=product_reviews_write&products_id=47&cPath=1
#1  require(/01/includes/templates/responsive_classic/templates/tpl_product_reviews_write_default.php) called at [/01/includes/templates/responsive_classic/common/tpl_main_page.php:178]
#2  require(/01/includes/templates/responsive_classic/common/tpl_main_page.php) called at [/01/index.php:94]
--> PHP Notice: Undefined index: customer_id in /01/includes/templates/responsive_classic/templates/tpl_product_reviews_write_default.php on line 38.
    if ($_SESSION['customer_id']) {

Request URI: /01/index.php?main_page=product_reviews_write&products_id=47&cPath=1
#1  require(/01/includes/templates/responsive_classic/templates/tpl_product_reviews_write_default.php) called at [/01/includes/templates/responsive_classic/common/tpl_main_page.php:178]
#2  require(/01/includes/templates/responsive_classic/common/tpl_main_page.php) called at [/01/index.php:94]
--> PHP Notice: Trying to get property 'fields' of non-object in /01/includes/templates/responsive_classic/templates/tpl_product_reviews_write_default.php on line 45.
--> PHP Notice: Trying to access array offset on value of type null in /01/includes/templates/responsive_classic/templates/tpl_product_reviews_write_default.php on line 45.
--> PHP Notice: Trying to get property 'fields' of non-object in /01/includes/templates/responsive_classic/templates/tpl_product_reviews_write_default.php on line 45.
--> PHP Notice: Trying to access array offset on value of type null in /01/includes/templates/responsive_classic/templates/tpl_product_reviews_write_default.php on line 45.
    <div id="textAreaReviews"><?php echo sprintf(SUB_TITLE_REVIEW, $customer->fields['customers_firstname'], $customer->fields['customers_lastname']); ?></div>

Request URI: /01/index.php?main_page=product_reviews_write&products_id=47&cPath=1
#1  require(/01/includes/templates/responsive_classic/templates/tpl_product_reviews_write_default.php) called at [/01/includes/templates/responsive_classic/common/tpl_main_page.php:178]
#2  require(/01/includes/templates/responsive_classic/common/tpl_main_page.php) called at [/01/index.php:94]
--> PHP Notice: Undefined index: customer_id in /01/includes/templates/responsive_classic/templates/tpl_product_reviews_write_default.php on line 58.
    if (!$_SESSION['customer_id']) {