To access the following services (Authorization, Capture, Refund, Cancel, Authorise3ds, Preauth transactions status, Non-3ds payments ) successfully, you simply need to pass Basic authentication
Basic authentication is a simple authentication scheme built into the HTTP protocol.
The client sends HTTP requests with the Authorization header that contains the word Basic followed by a space and a base64-encoded string publicKey:privateKey.
The token is gotten like this, base64Encode(publicKey:privateKey);