In the same screenshot under the "What is an App/Integration key" the second paragraph shows that you create these keys in a Sandbox and then promote them to Production through a Go Live Process. Also suggest you need to have an enterprise account or API plan. So the first question, is this a Sandbox?

No this is not sandbox.

As I understand it from the intention of the feature, you would move the integration key from a Sandbox after it was thoroughly tested and approved per the Go Live Process. I would suggest creating a DocuSign Support case to determine best next steps on acquiring a Sandbox for this purpose.

Hi,

I have created sandbox and I am able to generate integrator key and public/private key.

Now I am trying to call api(java) using that key and private key but it is giving me error.

https://stackoverflow.com/questions/54666259/java-docusign-authentication

Glad you were able to generate keys in the Sandbox. I think you posted the error to the correct forum, as I do not use the API specifically so I am not sure I could help. But I would suggest a new thread with the error, perhaps someone has seen the error before.