How can I compile a 64-bit executable file?

Hi, 

A2B Software for Linux product page download section has two files which are "Download  x86 bundle" and "Download  amd64 bundle". The website is as follows:
www.analog.com/en/design-center/evaluation-hardware-and-software/software/a2b-software.html

using "Download  amd64 bundle" file, The 'a2bapp-Linux' executable file I compiled was also 32-bit.

so, How can I compile a 64-bit executable?