The GTSRB dataset can be freely obtained from http://benchmark.ini.rub.de/?section=gtsrb&subsection=dataset (see the Dataset attribution section for attribution details).
You can find the code that we present in this chapter at our GitHub repository: https://github.com/PacktPublishing/OpenCV-4-with-Python-Blueprints-Second-Edition/tree/master/chapter7.