To access Symbl.ai's WebSocket for real-time audio transcription, developers need to register for an account and authenticate using their appId and appSecret. This authentication process allows users to receive their x-api-key, which is necessary for accessing the WebSocket. The x-api-key enables developers to choose from different types of message objects, such as recognition_result or message_response, depending on their specific use case. Recognition_result is suitable for live captioning, while message_response is better suited for transcripts or beyond. By understanding the differences between these message objects and following the guide provided by Symbl.ai, developers can effectively utilize the WebSocket to access real-time audio transcription services.