UnityWebRequest request = UnityWebRequest.Get("'ory-http/self-service/registration/api");

yield return request.SendWebRequest();

FlowResponse flowResponse = JsonUtility.FromJson<FlowResponse>(request.downloadHandler.text); // Flowresponse contains just 'id' field

string completeRegistrationUrl = $"{ory-http/self-service/registration?flow={flowId}";

            RegistrationRequest requestObject = new RegistrationRequest
            {
                traits = new Traits
                {
                    email = email,
                    username = "name",
                },
                password = password
            };

            string jsonBody = JsonUtility.ToJson(requestObject);

            Debug.Log($"Registration JSON: {jsonBody}");

            UnityWebRequest request = new UnityWebRequest(completeRegistrationUrl, "POST");
            byte[] bodyRaw = System.Text.Encoding.UTF8.GetBytes(jsonBody);
            request.uploadHandler = new UploadHandlerRaw(bodyRaw);
            request.downloadHandler = new DownloadHandlerBuffer();
            request.SetRequestHeader("Content-Type", "application/json");

            yield return request.SendWebRequest();

            if (request.result != UnityWebRequest.Result.Success)
            {
                Debug.LogError($"Error sending request: {request.error}");
                Debug.LogError($"Response code: {request.responseCode}");
                Debug.LogError($"Response: {request.downloadHandler.text}");
                yield break;
            }

{
  "error": {
    "id": "security_csrf_violation",
    "code": 403,
    "status": "Forbidden",
    "request": "134a2d69-553a-9bb0-9baa-68b55707c866",
    "reason": "Please retry the flow and optionally clear your cookies. The request was rejected to protect you from Cross-Site-Request-Forgery (CSRF) which could cause account takeover, leaking personal information, and other serious security issues.",
    "details": {
      "docs": "<https://www.ory.sh/kratos/docs/debug/csrf>",
      "hint": "The anti-CSRF cookie was found but the CSRF token was not included in the HTTP request body (csrf_token) nor in the HTTP Header (X-CSRF-Token).",
      "reject_reason": "The HTTP Cookie Header was set and a CSRF token was sent but they do not match. We recommend deleting all cookies for this domain and retrying the flow."
    },
    "message": "the request was rejected to protect you from Cross-Site-Request-Forgery"
  }
}