The web driver's address you've specified is the address of the ubuntu instance in AWS.
You've to specify the web driver's address according to the machine in which you run the test. As in, if you're testing it in your default machine (windows/mac os x, etc), you've to specify the path of webdriver accordingly.
When trying the test in the instance, you might need a jar file in the instance. So, before you export the jar file to that instance, you need to alter the address of the webdriver accordingly.
Conclusion: Specify the path of the web driver according to the system that you're testing.
For more information, check out this selenium tutorial.