Which controller for the Stepcraft 840?

I didn't get the UC100 board as I don't want to get a Windows PC just for the machine, and would prefer to control the machine from a Raspberry Pi, and initially been trying to get it to work using my Mac.
What controller would be recommended for this?

I got an Arduino Nano running GRBL wired to a parallel connector from a friend, but it doesn't work though I think it's wired correctly. While searching around I've found Tiger GRBL-SC and MDLCNC Estlcam Interface, which look like plug and play solutions for this. BUT I am a total noob (first CNC machine), and I'm not quite sure what would be best.

If there's some guide on how to set everything up, that would be awesome!