Since the PS4 does not support PS2 discs natively, you have to use an emulator-based "port" created by the homebrew community.
, which offers better hardware compatibility and custom song support. Installation Notes Jailbreak Required guitar hero 2 ps4 pkg hot
There is no official PKG for PS4 because the game was never released for that console. However, if you are using a modified (jailbroken) PS4, you can create a custom PKG using the original PlayStation 2 game files. How to Play Guitar Hero 2 on PS4 Since the PS4 does not support PS2 discs