You are chosing the hard way to demo Apex to your customer. You might as well use apex.oracle.com to do your demo. It is free and you do not have to set up anything yourself.
That said, if you have your DB running on OCI (which version?) you are almost there. The database already has Apex installed, so the only thing to setup is ORDS.
Just download ORDS and follow the instructions in the manual to connect it to your database and Apex instance. For your demo purposes you may choose to run ORDS stand-alone, so do not deploy it on WebLogic or Tomcat. Do not forget to open the ORDS port in your firewall.
If you want a later version of Apex than the one that comes with the database you could install it and upgrade the existing one, it has all been described in the manuals.