GET cases/{caseSystemId} works in postman, always returns 401 in php

I am trying to get a simple get request to work in php, that I've accomplished with postman without issue.

In postman, the outputted http code is the following:

GET /v1/cases/0a599156-6eb7-1e40-9bb3-2aae00039721 HTTP/1.1
Host: rms-world-check-one-api-pilot.thomsonreuters.com
Date: Fri, 06 Dec 2019 16:22:22 GMT
Authorization: Signature keyId="0b8f7e24-16d0-4672-9234-9b07b84d90d3",algorithm="hmac-sha256",headers="(request-target) host date",signature="N48t26VhJFS9KQZOqqIRumanWxfZEWwzJcRDF76f07c="
User-Agent: PostmanRuntime/7.19.0
Accept: */*
Cache-Control: no-cache
Postman-Token: d193cb45-f40d-4231-ad73-a203f00357b9,be6e8a64-807b-4184-88d3-fb1a0772b282
Host: rms-world-check-one-api-pilot.thomsonreuters.com
Accept-Encoding: gzip, deflate
Connection: keep-alive
cache-control: no-cache

my php code is as follows:

$curl = curl_init();

    curl_setopt_array($curl, array(
      CURLOPT_URL => "https://rms-world-check-one-api-pilot.thomsonreuters.com/v1/cases/0a599156-6eb7-1e40-9bb3-2aae00039721",
      CURLOPT_RETURNTRANSFER => true,
      CURLOPT_ENCODING => "",
      CURLOPT_MAXREDIRS => 10,
      CURLOPT_TIMEOUT => 30,
      CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
      CURLOPT_CUSTOMREQUEST => "GET",
      CURLOPT_POSTFIELDS => "",
      CURLOPT_HTTPHEADER => array(
        "Accept: */*",
        "Accept-Encoding: gzip, deflate",
        "Authorization: Signature keyId=\"0b8f7e24-16d0-4672-9234-9b07b84d90d3\",algorithm=\"hmac-sha256\",headers=\"(request-target) host date\",signature=\"N48t26VhJFS9KQZOqqIRumanWxfZEWwzJcRDF76f07c=\"",
        "Cache-Control: no-cache",
        "Connection: keep-alive",
        "Date: Fri, 06 Dec 2019 16:22:22 GMT",
        "Host: rms-world-check-one-api-pilot.thomsonreuters.com",
        "cache-control: no-cache"
      ),
    ));

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

    curl_close($curl);

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

    echo print_r($info);

And $response is always blank, and $info always shows me a 401 status code.