I was able to successfully complete the lab by following the instructions given in the lab module of the on-demand course. To create the data source using Virtual Machine, try to create a JSON data source using
http://data-server:8080/sales-ws/sales/ as the http url.You can replace the data server with the ip address if you have not configured the host file.
If you are using other options to complete the lab, then the web service "sales-ws" is available in http://localhost:8081/sales-ws/sales/. If the port is already in use then you can edit the start.sh file to change the port and try again to create the data source. The HTTP error code: 503 indicates that the server you are trying to connect is currently unable to handle the request, so please try again to establish the connection and ensure the start.sh script is running without throwing any errors.
If the issue persists then you can check the vdp.log located in <Denodo-Home>/logs/vdp for more information about the error.
Hope this helps!!