If you find a download claiming exactly 100MB with all stadiums and commentary intact, it is almost certainly or a virus.

The end result would be a fast-paced, strategy-focused football game that's easy to play in short bursts. Its tiny file size would make it accessible to players with limited storage or slower internet connections.

Released by Konami in 2007, this installment introduced several technological leaps for the franchise: PES 2008 PC MASTER LEAGUE [4K 60FPS] PES 2008 PC MASTER LEAGUE [4K 60FPS] YouTube·GAME RECORD TR Pro Evolution Soccer 2008 Review - GameSpot

If you want, I can:

To reach a tiny size like 100MB, developers of these repacks often "rip" (remove) non-essential files such as announcer commentary, soundtrack music, and high-definition cinematics. The Trade-off:

Instead of risking malware with sketchy 100MB PC rips, consider cleaner, optimized alternatives. 1. PES 2008 PPSSPP (PSP Emulator)

Versions that exist are either the full game split into many parts or significantly reduced versions for mobile platforms. Downloading any 100MB file claiming to be the full PC game is highly likely to be a scam or malware. To genuinely experience PES 2008, use legal channels or reputable digital marketplaces to ensure a safe and complete gaming experience.