Following the installation manual I can't do the step
sudo echo 'deb http://download.owncloud.org/download/repositories/production/Ubuntu_16.04/ /' > /etc/apt/sources.list.d/owncloud.list
which even with sudo rights outputs
-bash: /etc/apt/sources.list.d/owncloud.list: Permission denied
on a fresh Ubuntu 16.04 installation.
this is a pretty basic linux operations question. If you lack permissions you are not allowed to.
If you cannot sudo - do this as root.