1. 1
   2.1.2. Configuring the Apache HTTP Server Installation
   3.1. Download and Extract Apache HTTP Server
   4.1. Download and Extract Apache HTTP Server

   The httpd directory created by extracting the ZIP archive is the top-level directory for Apache HTTP Server. This is referred to in this documentation as HTTPD_HOME.
   

   This is not correct.

When you unzip a jbcs zip file u`ll get jbcs-httpd-2.4, but
RHEL
HTTPD_HOME should be jbcs-httpd-2.4/httpd
WINDOWS and SOLARIS
HTTPD_HOME should be jbcs-httpd-2.4

1. 2
   4.2. Configuring the Apache HTTP Server Installation

   Running the Apache HTTP Server Post-Installation Script
   
       Open a shell prompt, and change to the HTTPD_HOME/etc directory.
   
       Run the following command:
   
       sh .postinstall.httpd
   
       The post-installation script creates the Apache user and group. 
   

There should be mentioned to run postinstall with sudo aka as root. As you cannot create user Apache without root privileges and run successfully postinstall without root in /opt directory as recommended.