Once the download is complete, follow these steps to install Unreal Engine 4.12:
If you are working on an older machine or a laptop without a dedicated high-end GPU, 4.12 is significantly "lighter" than version 4.27 or 5.0. It allows for a smoother workflow on mid-range hardware. Learning the Fundamentals
Unreal Engine 4.12 supports macOS 10.11 (El Capitan) but does not support Apple Silicon (M1/M2/M3) natively. You would need to run it via Rosetta 2, which is unstable.