The map looks mostly 3d, the water looks like it was a post background image and the trees behind the town map title looks like they could have been photoshoped in. you can always start with Blender for the 3D stuff. 2.8 beta is out and it is more user friendly than older versions of blender.
heres some collection of houses you could use
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(more cartoony buildings)
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and you can search for more free things ready to be used by blender. they include things like trees, terrain, car's, etc.
you can also search other sites, but most other sites are not blender focused, so it takes a bit more work to import the files.