Thank you for buying the plugin! I’m glad you like it 
That logic you quoted, you’ll set it up in your material. The one you pass the textures to after using Create Dynamic Material Instance.
In a material, create two texture parameters, one for the BICS texture and one for the Color.
From the BICS texture, get the R output and multiply it by 255, to convert Unreal’s 0 to 1 range into the actual 255 that this texture represents. Then, you can use If nodes in the material to set the Opacity output depending on the user index you’re getting from the texture. You could make it visible for any user by setting the output to 0 for any values greater than 5. Or you could add a Scalar Parameter to control which user you want to have visible via Blueprint.
The Color texture, use it as Emissive output in the material.
Then, in your Blueprint, apply that material to the plane that will represent your green screen and set the texture parameters after creating the dynamic material instance.
I made this tutorial a while ago, about controlling materials from Blueprints. My English was barely decent and I still had the terrible idea of having a background track, but I hope it can help.
Cheers