It requires some minor fixes but I got it to work in 4.25.
I believe it required the fixes in these two threads (as I recall):
https://forums.unrealengine.com/development-discussion/rendering/1606958-4-22-mesh-drawing-pipline-breaks-imposter-materials
https://www.reddit.com/r/unrealengine/comments/dragk9/found_a_fix_for_ryan_brucks_octahedral_imposters/
There’s also a few people who have forked the project on github with fixes, though I didn’t try them.
I was really hoping Epic would integrate this into the engine at some point because it’s a beautiful solution.