How create php with client credential to retreive Token from header

To receive an access token, the client POSTs an API call to Edge with the values for client ID and client secret obtained from a registered developer app. In addition, the parameter grant_type=client_credentials must be passed as a query parameter.

@pistle2020 Hello, thank you for your answer: The Body to send is a jSon format:

{
	"grant_type": "client_credentials"
}

I use Insomnia to generate this PHP cURL Script Here is my PHP cURL script:

$curl = curl_init();
curl_setopt_array($curl, [
  CURLOPT_URL => "https://localhost/access-token",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => "{\n\t\"grant_type\": \"client_credentials\"\n}",
  CURLOPT_COOKIE => "dtCookie=v_4_srv_2_sn_6BC691EA47E4B3612884E99AB3D8EB3B_perc_100000_ol_0_mul_1",
  CURLOPT_HTTPHEADER => [
    "authorization: Bearer 55d4f5s5-dff4-56dsf54-dsdfsdf",
    "content-type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);
if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}
###########################

The result of this sccript is:

{
  "message": "Invalid Authorization header"
}

But i can see in the Insomnia GUI the generates Token. My Problem is, how to get the token in variable a use it.