The fundamental issue with this "download" is that Euro Truck Simulator 2 is a PC game built on a complex engine that requires significant RAM and processing power. The PSP (PlayStation Portable) was a handheld console from 2004. The PPSSPP emulator is specifically designed to run PSP games.
If you already own the real Euro Truck Simulator 2 on Steam, you can play the full, uncompromised game on your phone: Euro Truck Simulator 2 Ppsspp Zip File Fixed Download