DocuSignAPI请求授权代码PHP cURL重定向失败

Question

I'm attempting to complete "2. Configure Client and Request Authorization Code" of the DocuSign Setup and Authentication process.

Although the cURL command line example is there, no PHP code is shown. I've assembled what I believe to be the correct PHP code but the result which should be "A successful call results in the user being redirected in a browser to a standard DocuSign authentication page" does not occur.

Here is my code

$curl = curl_init();

curl_setopt_array($curl, array(
    CURLOPT_RETURNTRANSFER => 0,
    CURLOPT_FOLLOWLOCATION => 1,
    CURLOPT_URL => 'https://account-d.docusign.com/oauth/auth?response_type=code&scope=signature&client_id=[HIDDEN]&state=a39fh23hnf23&redirect_uri=[HIDDEN]'
));

$resp = curl_exec($curl);
curl_close($curl);