Once turned on the appliance will boot. The boot process of the virtual appliance can be monitored in the hypervisor (VirtualBox or VMWare).
After the boot process is completed you can log into the system locally using the console. The default login is user: mageni with password: mageni.
You can see the IP address running the command ifconfig
SSH is enabled by default. Now using the IP address shown by the ifconfig command, you can log into the appliance via SSH with the command: ssh@<IP> (Please note that, in your case, the IP could be different and that if you are using Windows you'll need a SSH client like Putty).
Now you can change the default password running the command passwd os