Complete the main story once. Alternatively, download a 100% save file ( .ppsspp format) from a trusted emulation forum and place it in /PSP/SAVEDATA/ .
Assuming you have a legal backup or are sourcing a clean ISO from a trusted archive (ensure it’s the US or EU version to avoid region-lock issues), follow this complete guide. Resident Evil 4 Download For Android Ppsspp
However, purists should note that the PSP version has notable differences from the HD remasters found on modern consoles: Complete the main story once