Copy contents of release/otls to any of your otl locations: for example, your houdini user folder: /home/username/houdiniXX.Y/otls (Linux) C:\Users\username\Documents\houdiniXX.Y\otls (Windows) folder (create otls subfolder if it doesn't exist) and you are good to go! (XX.Y will be your houdini version number, like 17.0 or 17.5)
Examples available in release folder
a number of assets here are implementing lorentz transformations, light doppler effects and other special-relativity-related light aberrations.
check out the video explanation here: a link to the video, a link to some text
examples for those assets are added to special_relativity_examples under the release folder