import requests
response = requests.get('<external url', auth=('<username>', '<password>'))
data = response.json()
html = data['list'][0]['attachments'][0]['url']
print (html)
data = requests.get('<API URL to download the attachment>', auth=('<username>', '<password>'), stream=True)
print (data.content)

<url to download the binary data>
x00x00x13x00x00x00x00x00x00x00x00x00x00x00x00x00x0fxcbx00x00x1ex00x1ex00xbex07x00x00.xcfx05x00x00x00'

import requests
import shutil

response = requests.get('<url>', auth=('<username>', '<password>'))
data = response.json()
html = data['list'][0]['attachments'][0]['url']
print (html)
data = requests.get('<url>', auth=('<username>', '<password>'), stream=True)
with open("C:/myfile.docx", 'wb') as f:
    data.raw.decode_content = True
    shutil.copyfileobj(data.raw, f)