If you are logged in and view a package (eg. https://pkghub.io/users/limi/projects/snzip/packages/f3d-snz...), there's a download link on the right under 'Meta'. It's just hidden if you are logged out, but the download link itself doesn't require you to be logged in, so you can copy paste that to a terminal (it does seem to lose the filename though, I've logged a bug for this).