使用Youtube API v3获取视频列表

I'm using this API to fetch all videos from my channel

https://www.googleapis.com/youtube/v3/playlistItems?part=snippet&maxResults=50&playlistId={my_playlist_id}&key={my_API_key}

but it can only get public videos. In Google developer page, I can authorize and get all videos but in my PHP code, I don't know how to do that. I tried to use curl but it didn't work. I think I must place access token somewhere but I don't know. Can anyone help me? Below is my code:

public function listVideos()
{
    $apiKey = 'my_API_key';
    $playlistId = 'my_playlist_id';
    $token = $this->getAccessToken(); // custom from Youtube API code
    $req = "https://www.googleapis.com/youtube/v3/playlistItems?part=snippet&maxResults=50&playlistId={$playlistId}&key={$apiKey}";

    $ch = curl_init();
    curl_setopt_array($ch, [
        CURLOPT_URL => $req,
        CURLOPT_USERAGENT => 'Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:61.0) Gecko/20100101 Firefox/61.0',
    ]);
    $data = curl_exec($ch);

    if ($data == false) {
        $this->messages = ['error' => curl_error($ch)];
        return $this->messages;
    }
    curl_close($ch);
    return $data;
}