I am using rhino 6. after a serverupdate all the Grasshopper Plugins I had installed were gone. Now, I tryed to install Lunchbox again (I had no problems when I installed it for the first time) via File > special folders > components folder.
I put the lunchbox file in: App Data > Roaming> Grasshopper > libraries
(I remember the first time there were much more files in this folder compared to now.)
Use the version with an installer. (Read the download descriptions) seems you are downloading the zip version. With zip version All those files should go into the special folders > components folder, not just the green .gha’s (and also make sure you have unblocked them if they are blocked)