There’s a Notion desktop app for both Mac and Windows, which can be downloaded here. You don’t need to use them, though: Near enough the same suite of features can be accessed online through Notion for Web using a browser like Google Chrome.
Truth be told, Notion for Web actually delivers a more seamless experience if you’re using the Notion Web Clipper. That’s because it’s instant. You don’t need to wait for an application to fire up to view a clipping; it’ll open up in a new browser tab.
It’s not like Notion for Mac or Notion for Windows have a calling card. Whether you’re using Desktop or Web, you’ll need to open the pages you want to access while you’re offline before you disconnect. The experience is very much the same on both.
Notably, there isn’t a Notion application for Linux. Users trying to access the service on this operating system will need to use Notion for Web to do so.