Virtualbox Ubuntu Image Username / password

First of all I am totally new to Linux. I decided to load Ubuntu Linux on Virtualbox and found an ova file here:

https://insights.ubuntu.com/2015/01/15/snappy-ubuntu-core-now-on-the-hypervisor-of-your-choice-with-ova/

It runs fine but when it boots up it is asking for a username / password. I've looked around and can't seem to find it. Can someone help me out?

Thanks!