It wasn't an official release, of course. It was a "mod"—a labor of love created by a group of fans who had taken the engine of FIFA 14 (the last official PSP version) and meticulously reskinned it. They had hand-coded the transfers, drawn the new 2016/17 kits pixel by pixel, and even swapped the soundtrack to match the console version.
Enthusiasts typically search for "highly compressed" ISO or CSO files on community forums like Fifa 17 Psp Iso File Download