Where can I find oauth_access_token?

Hi,
We need to create an external form that can register users to zoom webinar via API.

In this page we don’t understand how to find the oauth_access_token parameter.
We’d like to use the simplest way.
We tried with Oauth app but we don’t understand where is that parameter, and also with JWT, but it doesn’t work.
Maybe is code bug.
So, here’s the code:

//PHP CODE
$curl = curl_init();

    $data = array("email" => "email, "first_name" => "first name", "last_name" => last name);
    $data_string = json_encode($data);

    curl_setopt_array($curl, array(
    CURLOPT_URL => "https://api.zoom.us/v2/webinars/117-389-454/registrants",
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_ENCODING => "",
    CURLOPT_MAXREDIRS => 10,
    CURLOPT_TIMEOUT => 30,
    CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
    CURLOPT_CUSTOMREQUEST => "POST",
    CURLOPT_POSTFIELDS => $data_string,
    CURLOPT_HTTPHEADER => array(
        "authorization: Bearer {HOW CAN I GET THIS PARAMETER?}",
        "content-type: multipart/form-data;"
    ),
    ));

    $response = curl_exec($curl);
    $err = curl_error($curl);

    curl_close($curl);

    if ($err) {
        //echo "cURL Error #:" . $err;
    } else {
        //echo $response;
    }

Error
The error is: cURL Error #:SSL connect error

There are two different approaches to obtaining an access_token, each is dependent upon how you’re using the tokens/app:

JWT APPS
If you’re ONLY trying to register users in YOUR OWN Zoom account’s webinars, then I would recommend you use a JWT app, and follow this documentation to get your access_token: https://marketplace.zoom.us/docs/guides/authorization/jwt/jwt-with-zoom. JWT App are ONLY to be used by TRUSTED Backend Systems (never for front-end code or multi-tenant applications).

OAuth Apps
If you’re building an app that you intend to publish on the Zoom Marketplace for other Zoom Customers to install and use with their Zoom accounts, then you would need to build an OAuth2 App: https://marketplace.zoom.us/docs/guides/authorization/oauth/oauth-with-zoom