This release rewrites the installer in Go for a more coherent experience. With this, we've also gained macOS and Linux support!
If you're on macOS, please note that macOS may say the app is damaged and can't be opened. If that is the case, you will need to use xattr to tell macOS the app is safe. A tutorial for this can be found here. If you cannot install neptune after opening the app, make sure the neptune installer app has the "Full Disk Access" permission in system settings.
For Linux users: you'll need to run it as root. Not much I can do about that.