The standard MT5 installer from the official website is a "web installer". When you run it, the program automatically detects your system's bit architecture (32-bit vs. 64-bit) and downloads the appropriate files. Download the MetaTrader 5 trading platform for free

: The installer automatically detects your operating system's bit architecture (32-bit or 64-bit) and installs the appropriate version for your machine.

Because most broker websites auto-detect your OS and serve the 64-bit version, you need to force the download of the 32-bit installer.