When opening it, it crashes. The application doesn’t open in time and just crashes. Etterna used to say no noteskins found but after adjusting a few things it just instantly crashes. Im on MacOS Big Sur btw.
I can help you with this on the Discord if you want.
(I’m one of the macOS developers for Etterna)
Just ping me 
(I’m @bluebandit on it)
i redownloaded and it worked sorry for the late reply and thanks for offering to help