Searching for "exclusive" crack downloads for software like Festo FluidSim 5 is highly risky and generally leads to malicious websites.

If you're looking for solid (3D) modeling and simulation tools that are free or more accessible:

Instead of a license key, the download often contains malware or ransomware . While the software might appear to work, a Trojan could be quietly logging keystrokes to steal banking info or passwords.