The download link for Section 1 Unit 21 seems to be wrong. It downloads a different script, not the one written in Section 1 about the Bollinger bands strategy. Please fix the download link.
The code given in section 1 Unit 21 is sample Bollinger bands strategy which you can run on the Interactive Brokers.
You can find the code of section 1 Bollinger bands strategy in Section 10 Unit 2 (Downloadable Resources).