The way Corona-Warn-App works is very close to other apps like Immuni and Stop Covid France. First you sign up on the platform and identify whether you're a carrier of the virus or not. This allows you to create a tracking network that alerts citizens in case of contact with someone that's been infected. However, you're going to need to have to have spent over 15 minutes nearby this person so that the utility can assess a possible risk of contagion.
Another aspect to take into account is that the data managed within the platform is totally confidential. In this sense, you'll only ever be identified by means of an encrypted code and no one will be able to know your actual identity. Plus, the stored parameters are automatically deleted within 14 days.
Corona-Warn-App is the best app for tracking COVID-19 in Germany. Downloading this tool and using it in large urban areas can be very helpful to prevent new virus outbreaks and to keep all new infection sources under control.