These instructions currently are for Debian 9 (or Ubuntu 16.04 TLS) only, because integration with these distributions is tighter/easier and they provide sufficiently modern versions of the required software (and at no cost), including security updates. We do provide notes on deploying the Shibboleth IDPv3 on RHEL/CentOS, though.
The installation instructions provided in this guide are specific to a deployment without Apache httpd, using Apache Tomcat as the only web server process (as Java Servlet Container and TLS/SSL-enabled webserver). Do not use this guide if you're determined to use Apache
httpd (which is also possible, but sufficiently documented elsewhere).
There is no point in duplicating the existing Shibboleth IDP 3.x documentation. The installation part of this guide is complete but the guide for configuration of a Shibboleth IDP is necessarily incomplete, as deployments can vary significantly and the IDPv3 has tons of (optional) advanced features. Please use the upstream documentation for further steps or more advanced configurations, as hinted at below.