Paprika for macOS runs in a local sandbox.
For Paprika 3, the data is stored at:
/Users/Username/Library/Group Containers/72KVKW69K8.com.hindsightlabs.paprika.mac.v3/Data/
For Paprika 2, the data is stored at:
/Users/Username/Library/Containers/com.hindsightlabs.paprika.mac/Data/Library/Paprika/
or (for earlier versions of macOS):
/Users/Username/Library/Containers/com.hindsightlabs.paprika.mac/Library/Paprika/
Note that the Library folder is hidden by default in Finder. If you don't see it, you can navigate to it by opening Finder, selecting Go -> Go to Folder from the menu bar, and then typing in: ~/Library