How/can you install an older version of Blender? How or can you install an older version of Blender? The current version you can install is 2.82a, although, I would like version 2.78c. I cannot find it on the website if it exists.
All release of Blender are still available for download, reaching back to the very first version of Blender for the IRIX operating system.

The files for Blender 2.78c can be found here.