TheBryster posted at 7:01PM Sun, 25 September 2016 - #4284785

Sorry if I'm stating the obvious, but don't you need to unzip it first?

No, you shouldn't have to. Usually with Blender add-ons if you use the "install from file" option in the user preferences Blender will unzip everything and put it where it goes. I just tried it with the Mitsuba exporter though and it doesn't work,exactly as the OP reported. The instructions for the add-on say to install it manually so I guess the normal process doesn't work with this add-on.

Here's the relevant section of the instructions:

Unpack this file and move the resulting mitsuba folder into your Blender scripts/addons folder. After restarting Blender and enabling the plugin in the addons preferences, you should be able to select Mitsuba as the currently active renderer. In the main scene tab, you will need to set the path to the main renderer executable (mitsuba.exe on Windows, Mitsuba.app/Contents/MacOS/mitsuba on MacOS, /usr/bin/mitsuba on Linux).

This process does not seem to work either though (at least in Blender 2.77), so I have no idea how you get this add-on installed.