Request with Postman works but app doesn´t

Question

I'm using an api that doesn't have auth0 yet and they have the security code sent through one of the soup parameters. The issue is as follows: I am doing POST through Postman, with the security code and everything works perfectly, it returns what I need and I code 200 The problem is that I have to do it from a website and with the same xml code it gives me a 500 error and that the security code is incorrect. I also tried https://reqbin.com/ and it does the same thing, error 500, I put the same headers and the same xml code. Any idea what I can do?

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Body>
    <WSGetUserRequest>
      <GetUserArg>
        <original_user_id_value>1</original_user_id_value>
        <original_user_id_name>1</original_user_id_name>
        <secret_key>SECRETKEY</secret_key>
      </GetUserArg>
    </WSGetUserRequest>
  </soap:Body>
</soap:Envelope>

Headers:

SOAPAction: urn:WSRegistration#WSGetUser
Content-Type: text/xml; charset=utf-8