What does the information keep decentralized? Explain on an example how this will happen with a scanned fingerprint for example?
The fingerprint is most likely a single file. This file will be stored in multiple instances on different computers. Of course, in encrypted form. Therefore, the data will be securely stored so that they are unlikely to be lost. This is a general principle for storing decentralized data. For more information you need to examine the technical documentation of the project, if any. For this project, I myself have not yet understood how the data decentralization will be realized. 
On the one hand, it is clear that the information will be encrypted. But on the other hand the blockchain allows you to track all the information. But what if hackers get the clients fingerprint data and can use it on their own?
Hackers will not be able to get the biometric data of your finger as they will be stored decentralized