This book has been written with vRealize Orchestrator 6.02 Appliance. However, as mentioned earlier, you can also use the vCenter 5.5 Appliance.
If you have a valid VMware vSphere or vCenter standard license, you automatically own Orchestrator. You just have to download the appliance.
To use this book, you will need a VMware vSphere vCenter. You can use the trial version that is available for download at www.vmware.com. Please note that at the time of writing this book, the vSphere 6 trial version gives you no access to vRealize Orchestrator.