Stooq has changed their policy and now require an API key for downloading data. The procedure:

1. Open https://stooq.com/q/d/?s=aapl.us&get_apikey
2. Enter the captcha code.
3. Copy the CSV download link at the bottom of the page - it will contain the apikey variable.
4. Append the apikey variable with its value to all requests, e.g.
https://stooq.com/q/d/l/?s=msft.us&i=d&apikey=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

The next Zorro beta will contain an entry in Zorro.ini for the Stooq API key.