I need someone to write a method to successfully call an api via http

There is a website online. [login to view URL] that currently allows you to modify the tempo (speed) of an audio file.
I am a half developer but I am struggling to make the current request to their api.

 1) It says you are supposed to post to [login to view URL] posting the audio file along with some params like format, etc

 2) The api is then supposed to give you back a file id in the request which you then poll using the request url: curl '[login to view URL](the file id given back in previous request) 

3) once ready you can then retrieve the file using the request url:
'[login to view URL]' 
But when i make the request via a java client the following happens. This is the logs Status: 200 Response: {"status":{"code":200},"process_summary":{"task":"process/elastique","warning":[],"output_info":{"peak_level":4.25,"clipped":"true"},"parameters":{"pitch_semitones":0,"tempo_factor":4,"formant_semitones":0}}} 
With the response as you can you I don’t get the file id back.

This is the api. [login to view URL] I would prefer it written in java as my application is in java I have attached a file full of curl commands. I used the demo here [login to view URL] to help you. In chrome inspector I copied all the http requests made in order for the whole operation to succeed