https://developers.docusign.com/
DocuSign will sends you an email to activate your account.
Once you are logged-in to the account, go to: Settings / Apps and Keys /
You will now need to add 'App & Integration Key' to generate an App & Integration Key:
Next, name your Integration:
Capture the API key.*
Once your request is approved, DocuSign requires you to make the account LIVE: