To download D5 for Rhino and start using features like LiveSync you'll first need to install the D5 Launcher.
The launcher acts as a hub to manage projects and downloads, with news for events, webinars and updates. But the bit we're focusing on is found in Workflow on the left and then Sync. You can also find the other software D5 can connect to.
If you have not already installed the main D5 render you will need to download and install that as well. The order does not matter but you will need it before you can use D5 in Rhino.
Once everything is installed go into Rhino and you will have a new floating toolbar which can be docked with the others to your liking. To start using your Rhino model in D5 first Sync the project using 'Connect to the D5 Render' or run the command 'D5LiveSyncStart'.
The new window that opens once starting the project is your render window that is a real-time render window.