How can I get my IP whitelisted?

I am looking to integrate Kalixa into a project that I am working on, but anytime I make requests to https://api.test.kalixa.com/api/v4/merchants/using the demo credentials, I get the following response:

<html>
<head>
    <title>Request Rejected</title>
</head>
<body>
    The requested URL was rejected. Please consult with your administrator.<br><br>
    Your support ID is: 15484549372238474366<br><br>
    <a href='javascript:history.back()'>[ Go Back ]</a>
</body>
</html>

Here are the demo credentials:

- **Merchant ID**: `KalixaAcceptDEMO`
- **Shop ID**: `KalixaAcceptDEMO`  
- **Username**: `KalixaAcceptDemoSystemUser`
- **Password**: `KalixaAcceptDemoPassword`

Am I doing something wrong or do I indeed need to have my IP whitelisted before using Kalixa's test environment?