The %appdata% shorthand translates exactly to C:\Users\[user]\AppData\Roaming, where [user] stands for your Windows username. From here, you can navigate into your .minecraft folder and into the saves directory.
Keep in mind that the AppData folder is hidden by default in File Explorer; you'll need to enable the Hidden items option in File Explorer (View menu) if you want to navigate there through the window.
Alternatively, you could just navigate to the directory using the short-hand in File Explorer and copy the current path from File Explorer into Chunky. You should get the same as I have said.