4k / 60 Hz refresh on LattePanda 864 w/ Ubuntu

I have a LattePanda Alpha 864, 8GB. I want to get it to work at a 4k / 60 Hz using Ubuntu. Right now, I am running a fresh install of Ubuntu 18.04.2. While it works at 30Hz, it doesn't give me the option to set it to 4K at 60 Hz.

I'm assuming I'm missing something -- either driver or configuration. Is there a guide or some kind of docs somewhere I can use to get this going?

Thanks!