Neo Load With Selenium : Derive the use path from selenium script

Hello,
I am trying to derive the neo load user path from selenium script by integrating it with Neo Load.
I made the selenium jar and added it as 'java_test_script'.
I passed argument as -Dnl.selenium.proxy.mode=Design

I see in the documentation that we need to pass another argument as -Dnl.design.api.url=http://localhost:7400/Design/v1/Service.svc/
Not very sure what is this and why it required ..

when i run it from neo load i get the exception as
Caused by: java.lang.RuntimeException: Issue contacting DesignAPI server.
and
Caused by: java.io.FileNotFoundException: http://localhost:7400/Design/v1/Service.svc//$metadata

I also tried running outside neoload by opening command prompt... and tried runnign the jar file using java -jar command .. but it also gives the same errors
Please let me know what wrong I am doing or what else argument need to be passed

Thanks,