The "PCSX4" project is a long-standing hoax. Real emulation projects are typically open-source and hosted on platforms like GitHub; PCSX4 uses a polished, professional-looking website to trick users into downloading "installers" that require "verification keys" obtained through malicious links.
Developed by the creators of the famous PS3 emulator (RPCS3), this is a research-focused Linux project. Summary of Safety Tips Download PS4 Emulator PCSX4
Emulating the PS4 is incredibly complex. While the PS4 uses an x86-64 architecture (similar to PCs), its custom OS and GPU hardware are difficult to replicate. Legitimate progress is being made, but it is not yet at a "download and play" stage for the general public. The "PCSX4" project is a long-standing hoax