Hello. How can I save spatial map for some space? I've found only how to render spatial maps in Unity
You can do this through the Device Portal. You go to the 3D view tab and click the Update button once you have mapped out your room pretty thoroughly you can save it and download the file to your computer. However, if you are trying to save / load a pre-scanned room through the app you can probably do this by attaching a world anchor to the room mesh possibly. It might already be done already in the MRTK.