Once you install OwnCloud you will see the following on the log in page:

You are accessing the server from an untrusted domain.

Please contact your administrator. If you are an administrator of this instance, configure the "trusted_domains" setting in config/config.php. An example configuration is provided in config/config.sample.php or at the documentation.

This is due to the template IP being hardcoded into the template, to fix simply edit the config.php file to include the IP of your server or the domain you wish to use on this server.

Or simply open a support ticket with our team with the details and we will make this change for you.