For functionality specific to the Unreal Editor and some in-depth knowledge, check out https://docs.unrealengine.com/en-us/Engine/Editor.
Follow the initial steps from Set up a VS level:
Create a new show
Make sure you are working in Video space
In Director check: SETUP > Show > Show settings > Compositing color space
Launch the level
Go to the Editor
Create a new empty level
Create a virtual scene
Add or import your 3D assets
XR set extension
If you plan an additional XR set extension, separate the graphics and XR content using a level streaming setup.
Learn more about how to Set up an XR set extension with translucent holdouts
Add XR wall
Add XR wall actors for all real world screens.
Add an "XR wall" to the level which can be found in Place Actors > Pixotope
Position and scale the XR wall to align with the real world LED walls
Enable WYSIWYG to make aligning the walls easier
Academy Tutorial - XR Manual Alignment
Learn how to align the XR walls in Pixotope with the physical LED wall
Choose output position
Select the XR wall and go to the "XR" section in the "Details" panel
Set “Output Position” to how the rendering of this XR wall should be output. These are the options:
Enable XR rendering
Go to the "Pixotope XR Compositing" section in the "World Settings"
Enable "Output XR to SDI"
To output the XR wall texture(s) also in the viewport and the computer monitor when in live mode, change the "Visualization Mode" in World Settings > Pixotope World from "Normal" to "Off-axis texture".
When using virtual camera moves, make sure to enable "XR From Current Camera" in World Settings > Pixotope XR Compositing.
Previous implementation with Off Axis plugin
Enable the plugin
Open the "Plugins" window via Edit > Plugins in the window menu
Click on the "Pixotope" category and enable "Pixotope Off Axis"
Restart the Editor
Add a Pixotope Off Axis Window from the Place Actors panel > Pixotope
Place and scale the window where you want your virtual window to be
Set the Local Player Class to "OffAxisLocalPlayer" in Project Settings > Engine - General Settings > Default Classes - Local Player Class
Save and restart the Editor
If your camera system uses a lens file, disable lens distortion in Director > Configure > Tracking > Lens Tracking > Advanced > Disable Distortion