GuzzleHttp\Exception\RequestException cURL error 60: SSL certificate problem

Following along with Laravel 8 From Scratch lesson 58. Mailchimp api Tinkering.

I got this error:

GuzzleHttp\Exception\RequestException

cURL error 60: SSL certificate problem: self signed certificate in certificate chain (see https://curl.haxx.se/libcurl/c/libcurl-errors.html) for https://us6.api.mailchimp.com/3.0/ping

Here is the code I ran:

Route::get('/ping', function () {
    /*ddd(config('services.mailchimp.key'));*/

    $mailchimp = new \MailchimpMarketing\ApiClient();

    $mailchimp->setConfig([
        'apiKey' => config('services.mailchimp.key'),
        'server' => 'us6'
    ]);


    $response = $mailchimp->ping->get();
    ddd($response);
});

I am using wamp server.