Lightning Wordpress Publisher and BTCPay -Fatal error: Uncaught Error: Class 'LightningChargeClient' not found

Hi, I have changed the setting from 'lnd' to 'clightning' to test out the LApps. I am on a LunaNode plan. Have enabled the Spark service. Under Manage Store, have also completed the Test Connection and is ok and saved the changes.

Downloaded Lightning Publisher in Word Press and updated the Lightning Publisher settings (server url, public url and API token) and saved changes.

I received an error message when firing up the website (website is working when the Lightning Publisher is deactivated) :

Fatal error: Uncaught Error: Class 'LightningChargeClient' not found in /home/domainname/public_html/wp-content/plugins/lightning-publisher/lightning-publisher.php:19 Stack trace: #0 /home/domainname/public_html/wp-content/plugins/lightning-publisher/lightning-publisher.php(195): Lightning_Publisher->__construct() #1 /home/domainname/public_html/wp-settings.php(322): include_once('/home/domainname/...') #2 /home/domainname/public_html/wp-config.php(90): require_once('/home/domainname/...') #3 /home/domainname/public_html/wp-load.php(37): require_once('/home/domainname/...') #4 /home/domainname/public_html/wp-blog-header.php(13): require_once('/home/domainname/...') #5 /home/domainname/public_html/index.php(17): require('/home/domainname/...') #6 {main} thrown in /home/domainname/public_html/wp-content/plugins/lightning-publisher/lightning-publisher.php on line 19.

Would appreciate help to resolve the issue. Thanks.