The "Booking Server endpoint and credentials" tab allows you to configure the endpoint URL, username, and password for your booking server. This tab is only accessible if you use the newest REST-based API v3 booking server.
All of Google's booking server requests are relative to the "Booking Server URL" set on this tab. For example, if your URL is set to "api.example.com/google", then all HealthCheck requests will be sent to "api.example.com/google/v3/HealthCheck".
Be sure to configure the correct booking server endpoint for each environment (production and sandbox).