Compiling from SVN for Cygwin
At the moment, there is no standard distribution for Cygwin. Therefore, if you wish to have a Cygwin-specific build of FreeBASIC, you'll have to build it yourself. You should only build for Cygwin if you wish to use a linux library that does not have a Windows port. I will not go over the details for installing Cygwin, if you need more information see http://www.cygwin.com/ .
After Cygwin is properly installed the Linux specific instructions found under Compiling from SVN for Linux should produce the expected results. Instead of running the installation script "install.sh" you should copy fbc.exe and the bin and lib directories to your installation directory.