1.5.6c - php 7.3.22

Getting this error alot, admin folder has been renamed.

Code:
[11-Sep-2020 17:10:02 Europe/London] Request URI: /admin/orders.php?oID=613520&action=edit, IP address: removed
#1  require(/home/store/public_html/includes/modules/payment/paypal/paypalwpp_admin_notification.php) called at [/home/store/public_html/includes/modules/payment/paypaldp.php:987]
#2  paypaldp->admin_notification() called at [/home/store/public_html/admin/orders.php:863]
--> PHP Warning: Use of undefined constant MODULE_PAYMENT_PAYFLOW_TRANSACTION_MODE - assumed 'MODULE_PAYMENT_PAYFLOW_TRANSACTION_MODE' (this will throw an Error in a future version of PHP) in /home/store/public_html/includes/modules/payment/paypal/paypalwpp_admin_notification.php on line 419.