I'm sorry about the issue. Unfortunately, Office version 2004 is very old; it's not compatible with OS X version 10.11, and if you have an upgrade of Office version 2011, you cannot install it without Office 2008. (If you have a full version (not upgrade version) of Office 2011, then you can install it directly.) Otherwise, you would need to get the latest version of Office.
Also, if you do not know yet, I can provide you an alternate office application that is free to use on Mac OS X 10.11.
Please reply at the box below to continue troubleshooting. Thank you.