Why is my megascan/ foliage not being affected by light/shadows?

[Rhitzz]

Have been playing around with the settings of my megascans and the directional light but the foliage doesnt seem to get that much shadow as the rest of the scene and looks out of place. can anyone help? for instance that area on the left should be darker.

also when i use post processing the foliage remains the same colour. the foliage is used from megascans

[Rhitzz]

even with the post process down and no light enabled the plants are always that colour and nearly glowing and throwing over the whole scene