If you are sticking with Windows 7, is the final stable release that offers full, native compatibility. It remains a robust tool for professional-grade schematic capture and PCB layout.
Ensure your GPU drivers are up to date. KiCad’s "Accelerated Canvas" uses OpenGL, which can be buggy on the default "Generic" Windows 7 drivers. Can you run KiCad 6 or 7 on Windows 7? Kicad For Windows 7
Completely free with no subscription or "lite" version limitations. If you are sticking with Windows 7, is
Most Windows 7 machines are 64-bit; look for the x86_64 installer (approx. 1.2 GB). and 10 in mind.
Version 5.1.x was built specifically with Windows 7, 8.1, and 10 in mind.