If you're trying to install Screenly OSE using the following command
$ bash <(curl -sL https://www.screenly.io/install-ose.sh)
and it silently dies, the reason is most likely that the time on your Raspberry Pi is incorrectly configured. To check this, simply run
Fri Jun 30 09:14:15 BST 2017
If you instead of the current year get 1979, this means your system failed to retrieve a date from the NTP server. This most commonly happens if you either plug in the ethernet cable after you have booted up the Raspberry Pi, or if your firewall is blocking NTP connections. If it is the former case, simply issue a reboot with the ethernet cable plugged in and you should be good.