These links show you how to install SI 2018.
Installing the SI 2018 Server
Installing Visio Optional. If you will be using any supported third-party software, we recommend installing Visio, AutoCAD, and QuickBooks on the all machines prior to installing the SI 2018 Client.
Installing an SI 2018 Client
Registration
Upgrading to SI 2018
Updating SI 2018
SI 2018 Release Notes