Thanks for your quick reply. You mean in for instance add it to Generated Level>Rooms>Walls?
While that probably would work on an existing level, but since you have to define the shape of the shadow caster manually (at least from what I know), it would not work in practice.
I was thinking it might work if you could add it directly to a single tile, then when you fuse corridors with rooms you could remove the shadowcasters from the colliding room tiles. No idea how to add it so a single tile though.
If you could somehow generate a Shadow caster that has the same shape of a shared wall tilemap layer, would probably be the best way.
Shadow casters are otherwise fairly simple to use, it does requires a Universal Render Pipeline project. This short video should help, link
edit: This guy seems to be on to something! link
Will see if i can try this out later