Using GreenLuma today is not worth the risk. Modern Steam updates have likely patched the specific exploits that version 3.0.3 relied on. Even if you get it running, you risk your Steam account and your computer's security.
Instead of searching for .rar files from 2018, explore legal alternatives or support the developers who make the games you love. If you are pursuing GreenLuma for academic interest, isolate the file in a virtual machine and never run it on a system with personal data. Greenluma-3.0.3-steam006.rar
Unlike traditional cracks that replace game executables, GreenLuma operates at the Steam client level. It allows users to launch games they do not technically own by tricking the Steam client into thinking the user has valid licenses (app IDs) or by unlocking DLC (Downloadable Content). Using GreenLuma today is not worth the risk