I can provide the exact download links or optimization steps for your hardware.

Install the latest version of Sideloadly on your computer.

Since the latest version of Subway Surfers requires modern iOS, you'll need a specific file (iOS App Store Package) that is compatible with 32-bit architecture and iOS 9 [13, 17].

A functional 30-pin or Lightning cable to connect your device to the computer.

Subreddits like r/LegacyiOS offer mega-threads and community-maintained Google Drives containing verified legacy IPAs.

iOS 9.3.5 devices run on 32-bit architecture, while modern iOS apps are strictly 64-bit.

To understand why you cannot simply download the game from the App Store, you need to look at the evolution of Subway Surfers.