How can I download the NRRD file of a specific mouse brain structure?

I’m new in this, and I’m not sure how to download data in nrrd format from a specific area of ​​the mouse cerebellum (Declive exactly). Can someone guide me a bit please?

If you are new to imaging, I would recommend getting started with the AllenSDK
Welcome to the Allen SDK — Allen SDK dev documentation

In particular, look this part
Reference Space — Allen SDK dev documentation