The latest released version of Octave is always available from
Packaged versions of Octave for GNU/Linux systems are provided by the individual distributions described in the Octave wiki. These packages are created by volunteers. The delay between an Octave source release and the availability of a package for a particular GNU/Linux distribution varies.
Alternatively, there are some distribution independent installation methods for more recent versions of GNU Octave described in the Octave wiki.
Executable versions of Octave for BSD systems are provided by the individual distributions. Both FreeBSD and OpenBSD have Octave packages. These packages are created by volunteers and the Octave project has no control over that process.
pkg listto list them.
Windows-64 (64-bit linear algebra for large data)
Unless your computer has more than ~32GB of memory and you need to solve linear algebra problems with arrays containing more than ~2 billion elements, this version will offer no advantage over the recommended Windows-64 version above.
All Windows binaries with corresponding source code can be downloaded from https://ftpmirror.gnu.org/octave/windows/.