Often called the "Legacy IDE," this version is officially compatible with Windows 7, 8.1, and 10. It is highly recommended for older systems due to its lightweight nature and stability. Step-by-Step Download and Installation
To download the Arduino IDE for Windows 8.1 64-bit, you must select specific versions because the newest releases (v2.2.0 and later) are generally incompatible with older Windows operating systems. Which Version Should You Download? There are two primary paths for Windows 8.1 users: download arduino ide for windows 8.1 64 bit
IDE 2.2.1 compatibility to Windows 8.1 64-bit ? - IDE 2.x - Arduino Forum Often called the "Legacy IDE," this version is
This is the last 2.x version with "incidental compatibility" for Windows 8.1. It includes modern features like auto-complete and a built-in debugger, but it is technically unsupported by the developer. Which Version Should You Download