Move the provided ppsspp.ini or "Fix" folder into the PSP/System directory on your device.
Standard mods often crash during 6-man matches or Royal Rumbles.
If you have downloaded a fix file, it generally needs to be placed within your PSP system directory rather than the game folder itself.
If the fix includes a SAVEDATA folder, copy it into PSP/SAVEDATA to ensure updated rosters and unlocked arenas are active.