In the DocuSign admin module you can configure “Connect” which is a webhook your app should be listening to. In the “Connect” configuration you can enter a URL to which DocuSign then sends messages. 

In your Mendix app you then create a REST service for that same URL so that you can process these messages. 

The link underneath gives a lenghty explanation on what you need to do to:

https://support.docusign.com/en/guides/ndse-admin-guide-connect?_ga=2.232432607.1143209282.1587973095-1902736503.1587457130

High level it comes down to this:

1. Check whether the caller is authorized to make the call
2. Process the incoming XML message using a Mendix mapping file
3. In case a recipient of the envelope completed the signing process, get the documents with a REST call to the DocuSign API. You can also choose to get the DocumentPDFs in the incoming XML message but those calls are getting really big then.

See the documentation:

Feature: Save signed documents in your Mendix app (when using embedded signing).
Limitation: Saving documents that are signed through remote signing is not yet possible.

So it depends on how you did setup this module.

Regards,

Ronald