import requests

url = "https://{FUSION HOST}/api/objects/substitutions"

payload = {}
headers = {"Content-Type": "application/zip"}

response = requests.post(url, json=payload, headers=headers)

print(response.json())

{
  "properties": [
    {
      "id": "<string>",
      "schema": {
        "type": "<string>",
        "title": "<string>",
        "description": "<string>",
        "hints": [
          "<string>"
        ]
      }
    }
  ],
  "values": {},
  "zipFileToken": "<string>"
}