Avoid. If you cannot pay for Adobe, use Darktable or RawTherapee – both are free, open-source, safe, and more powerful than Lightroom 5.4. If you need Lightroom’s exact workflow, consider the legitimate Adobe Photography Plan ($9.99/month) which includes Lightroom Classic, Lightroom CC, and Photoshop.
1/10 – High probability of malware. Even if the crack “works,” you are trusting an anonymous pirate with executable code.
It is not worth your system security or personal data.