Class "KlaviyoAPI\KlaviyoAPI" not found in Drupal\klavio_marketing\KlavioMarketingApi->__construct()

Problem/Motivation

The website encountered an unexpected error. Please try again later.

Error: Class "KlaviyoAPI\KlaviyoAPI" not found in Drupal\klavio_marketing\KlavioMarketingApi->__construct() (line 49 of modules\contrib\klavio_marketing\src\KlavioMarketingApi.php).
Drupal\Component\DependencyInjection\Container->createService(Array, 'klavio_marketing.api') (Line: 177)
Drupal\Component\DependencyInjection\Container->get('klavio_marketing.api') (Line: 61)
Drupal\klavio_marketing\Form\KlavioMarketingDashboard::create(Object) (Line: 28)
Drupal\Core\DependencyInjection\ClassResolver->getInstanceFromDefinition('\Drupal\klavio_marketing\Form\KlavioMarketingCampaigns') (Line: 48)
Drupal\Core\Controller\HtmlFormController->getFormObject(Object, '\Drupal\klavio_marketing\Form\KlavioMarketingCampaigns') (Line: 58)
Drupal\Core\Controller\FormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 580)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 163)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 74)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 58)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object, 1, 1) (Line: 686)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

Steps to reproduce

1>install the module
2>go to Administration >Configuration >Web services
3> click the campaigns and list tabs
get the error.