Octopus Plugin First Steps

Good afternoon everybody. I guess I need the octopus plugin for a more advanced project, but as I couldn't find any beginners Help for it, I tried myself:

I have this tiny little cube and I want it to have the largest possible volume with the smallest square meter sum of the outer faces.

Sounds easy I guess, but when the octopus window pops up I don't know what to do with the sliders and stuff. The Max volume is 8000 and the min sqm is 24. I tried to put those numbers in the fields beneath the generation slider, but without success.

Thanks for help!