Hello,
Sorry, but we don't have a whole sample using a stream with Symfony. phpdocx can be used with any PHP project, CMS, framework... the stream is generated as a generic stream.
We recommend you check the Symfony documentation about working with streams available on:
https://dev.to/rubenrubiob/serve-a-file-stream-in-symfony-3ei3
https://symfony.com/doc/current/components/http_foundation.html#serving-files
and also test step by step your code: if the DOCX stream is generated and returned correctly, if the stream is being captured correctly (and then if you can save as a fs or stream it).
Regards.