$ composer require league/flysystem-bundle
# config/packages/flysystem.yml
flysystem:
storages:
docusign.storage:
adapter: 'local'
options:
directory: '%kernel.project_dir%/var/storage/default'
You need to define as storage the name of the flysystem storage.
# config/packages/docusign.yml
docusign:
# ...
storage: 'docusign.storage'