Use the mymc utility or the built-in memory card manager in PCSX2 to import the save into your virtual memory card slot.
If you are playing on an original PS2 console, you can find physical memory cards pre-loaded with these save files from retailers like eBay and Etsy.
: General raw save format often used with modern memory card tools. .ps2 : Virtual memory card files for the PCSX2 emulator . Implementation Guide For PCSX2 (Emulator)