Using ETL tool's REST utility to download a folder with REST get URL

I tried to execute this time using POSTMAN as the tool I am using does not print the response. First Postman was not able to complete OAuth 2.0 authorization when I tried to generate the token. Nonetheless, I used the callback api and put it in the settings page and used the generated token. Then it gave me this error:

{
"error": "Must send either a from_path or a from_copy_ref"
}

I was giving parameters like root, from_path, to_path in the Body as JSON. I even tried to pass these parameters as headers, but still the same error.