@miikka1978 said:
Is there some limitations with the size of the model? For example, I would like to bake a golf course model (2000m x 2000m) and import the model into Unity. The file size is about 5-6MB.
No intrinsic limits. However, you can significantly accelerate your workflow by structuring your model, using Layers, "Zoning" your (golf) landscape into top-level Groups to make it easier to edit and process, using a consistent level-of-detail both in terms of geometry detail and texture detail (no 6000x6000 textures for the basket in the corner). etc.
Adam