Gaussian generates massive temporary files during calculations (such as two-electron integrals).
Right-click the downloaded .zip file and extract the contents to a temporary folder, or double-click the .exe installer. download+gaussian+16+windows+new
32-bit Version. Licenses for the 32-bit version of Gaussian 16W are available for single computers and as part of a site license ( Gaussian.com Support - Gaussian.com download+gaussian+16+windows+new