Using an Network Adapter and an internal HDD with Open PS2 Loader (OPL) is the most reliable way to play patched games.
Getting these custom builds to run requires a mix of specific hardware and software steps. Here is everything you need to know to get your PS2 pitch-ready. Understanding the "Add-on" Format winning eleven 49 addon ps2 work
On the PS2, an "add-on" isn't a DLC file like on modern consoles. It usually comes in one of two forms: Using an Network Adapter and an internal HDD