How to use SQL Server Reporting Services URL Access to save rendered PDF-Reports as varbinary into Table

I'm trying to store rendered pdf-reports from the Report Server back into a table of the origin database as a varbinary. My current approach would be to use URL-Access inside of an external python script to get the rendered reports and then save them into the corresponding table. The following URL works as expected in the browser:
http://localhost/reportserver?/ReportingServicesTest/Report_Test&rs:Format=PDF

However when I tried to access that URL inside of the external python script I received a 401 error.
So I then tried to use the requests_ntlm library to pass the username and password, but somehow it still doesn't work.

import requests
from requests_ntlm import HttpNtlmAuth

url = 'http://localhost/reportserver?/ReportingServicesTest/Report_Test&rs:Format=PDF'
session = requests.Session()
session.auth = HttpNtlmAuth('Domain\\Username','password')
response = session.get(url,stream=True)
open('C:/Path/Report_Test.pdf', 'wb').write(response.content)

Is my approach in principle correct or are there better ways to accomplish the same thing?
I'm fairly new to SQL Server Reporting Services, so I'm open to your suggestions and appreciate your help in advance.

IMHO if you need to historic data for safekeeping or auditing purposes I'd strongly recommend to keep the data in the database. Use a staging environment to add a timestamp to the report data so the snapshots make more sense. In this way you can use the SSRS portal later on to filter on a particular historic version (parameterized) and you don't have to build a bespoke PDF viewer. It would also save some database storage. As an alternative, you could create a subscription in SSRS, have the PDF send to a file share. Then configure a listener to that directory to get your meta information and store that reference in a database table. Needless to say I'm not a big fan of storing files in the database as file storage is cheaper than database storage most of the time.

To solve your authentication issue you might want to check up on your rsreportserver.config file on your web server as your current code suggests that your local host is unknowing of any domain. In any case you can try changing your <Authentication/> section so that it looks like this:

  <Authentication>
    <AuthenticationTypes>
      <RSWindowsBasic>
        <LogonMethod>3</LogonMethod>
        <Realm></Realm>
        <DefaultDomain>putyourfullyqualifieddomainnamehere</DefaultDomain>
      </RSWindowsBasic>
    </AuthenticationTypes>
    <RSWindowsExtendedProtectionLevel>Off</RSWindowsExtendedProtectionLevel>
    <RSWindowsExtendedProtectionScenario>Proxy</RSWindowsExtendedProtectionScenario>
    <EnableAuthPersistence>true</EnableAuthPersistence>
  </Authentication>

This will also work if your web server is behind a proxy or firewall.

Important: the content of DefaultDomain should be a FQDN, such as contoso.microsoft.com or myprimarydomain.lan