During the installation of OpenMeidaVault, there will be some configurations require user interactions. To assist the process, it's better to install whiptail package ahead of time if it's not already installed.
It will take quite a while for apt-get to retrieve and install all the required packages. During the process you are required to answer some questions for configurations, so don't wonder too far away.
Once the installation finishes, you won't have access via SSH after you log out the current session because by default OpenMediaVault doesn't enable any services. You will need to use your browser to visit your Pogoplug's IP address and sign in as "admin" with password "openmediavault".
There are several things you need to do first time you log in the OpenMediaVault Web Administration.
In System/General Settings, change your Web Administrator Password.
In System/Date & Time, set your Time Zone and whether to Use NTP server.
In System/Network/Interfaces, edit your network interface and click OK to make sure it's properly configured. Otherwise, the network interfaces won't show up in Diagnostics/System Information/Interfaces.
In Services, you can consider to enable whatever services you need.