This three year old blog post that you followed is using a 4 year old script to download and install owncloud. This script is trying to install PHP 5 (!!!), which has long been deprecated. So most likely the script already failed to install the packages. And even if it was successful installing PHP 5, ownCloud no longer supports it.
Perhaps somebody else in the forum here can recommend a more up to date guide to install ownCloud on a RaspberryPi.
Unfortunately I don’t have one, I’d love to test whether the official ownCloud ansible roles also work on a RPi…