How to retrieve an embedded html task form via a REST API call

Hi there,

I would like to retrieve (as a file) an embedded html task form, filled in with its values (as depicted in the following screenshot) via a REST API call (maybe like this method) Get Rendered Task Form | docs.camunda.org

I would like to make this call in a client (Postman) through a Service Task in order to convert (with a Java library maybe) afterwards the retrieved file (with the html form) to a pdf document.

As far as the required task_id is concerned, does anyone know if I must save it into a process variable ?
Could anyone guide me a bit on this please ?

Thanks in advance,
Steve