Get documents from DocuSign- envelopes give me error

I established a connection with Docusign, and want to retrieve documents from Docusign, but the below code gives me an error: looks like I need an envelope Id but I want to get the documents in bulk without specifying envelop id…

$base_uri+ “/restapi/v2.1/accounts/” +$account_id + “/envelopes/”

Failure: REST API service endpoint returned error result: status code = 400, Reason: REST API service endpoint returned error result: status code = 400, reason phrase = Bad Request, refer to the error_entity field in the error view document for more details, Resolution: Please check the values of Snap properties.

Any help would be appreciated!! Thank you!