Do not Google "PCSX2 download." Go directly to the official website and click the "Windows Nightly" or "macOS Nightly" button. Unzip it, point it to your BIOS (legally dumped from your own PS2, of course), and load your disc.
When you first launch the emulator, the Setup Wizard will guide you through: Language & Theme: Choose your preferred interface look. BIOS Selection: pcsx2 1.7.0 nightly