InstancedFoliageActor Problem

Hey there!
I’m doing a large map for a school project and in ran into a problem i don’t know how to solve…
So basically the whole map is covered in foliage(trees,grass,bushes…). I built the lighting and then the message log had a couple of problems with the lightmap of the foliage saying it’s to big. I have no idea on how to fix this and I need to get the whole thing up and running in a few weeks so help is much appreciated! Pic of the Message Log: