The recommended way to install QuTiP is with conda or pip, see the documentation for details .
If you are interested in legacy releases of QuTiP, you can download all previous versions from the GitHub page by selecting the desired source branch.
Instructions for installing QuTiP can be found in the documentation, or in the INSTALL.txt file included in the QuTiP source folder.
If you want to checkout the latest source code and documentation then head on over to the QuTiP repositories at github.com/qutip.