Go to the Qt 5.12.x Offline Archive and select the .exe file ending in x86 (e.g., qt-opensource-windows-x86-5.12.12.exe ). Installation Guide for Windows 7 32-bit
Since these are legacy versions, you will find them in the official Qt Archive:
The best version for a 32-bit Windows 7 environment is or Qt 5.12.x . These were the last major releases to officially support Windows 7 and provide 32-bit binaries.
Visit the Qt Online Installer Archive to find older versions of the unified installer.
Double-click the downloaded .exe file. You may need a Qt Account to proceed through the login screen.
Follow the remaining prompts to finish the setup. System Requirements