A decade later, the search term persists. Why? Because PES 2011 represents the peak of the "old school" PES philosophy before the series transitioned to the FOX Engine (PES 2014 onward) and eventually eFootball.
Most compressed games come in .7z or .rar formats. Use an app like ZArchiver to extract the ISO file to your internal storage.
If you're looking to play PES 2011 on PPSSPP, here are some steps: