We are sorry to hear you are having issues getting Ritmo to run on your Mac. We have not seen this in our testing and would like to ask you a few questions to help us narrow down what might be the problem.
1. What MacOS version are you running?
2. How did you download Ritmo? Through the itch.io client or from the webpage?
3. If you downloaded Ritmo directly from the webpage, which zip folder did you download? ritmo-win.zip or ritmo-mac.zip?