Question Crappy results with lightmapper in URP, tips?

Trying to bake some nice lighting for this apartment scene. The model is imported with generate UVs for lighting checked. Renderpipeline is URP in Uniti2020.1.17. Scene scale is correct, the window/glass is excluded from shadows. (the ceiling is missing)
Rendersettings default-highresolution.

However, this looks a little bit crappy!
What could be the problem here?








This is a test render in 3ds max, and sort of what I want to achieve with baked lighting:

 

I now see that "generate lightmap UV" gives non optimal results.. Though it shouldn't be the cause for the problems above.

Look at the ground for example in the picture on the top of my post, it is full of artifacts while it is just a plane.... Also in the UV layout (the yellow object):

 

You know what; I just tried Unreal with hardly any experience and get this.
I think I'll stick with Unreal for this one.. :/
I wonder if Unity has plans to update the UV generation for lightmaps? Unreal does it dynamically, even accounting for the lightmap resolution and adapting the padding between UVs to avoid bleeding as I understood it..

 

Ok thanks very much! I'll look into this and also try 2020.1++
Unreal is maybe nice for the graphics, but it certainly has its own pains