There's still something wrong with the Mac download; not only does it still not work at all (please, please, please fix your build issues), but it doesn't even contain the v0.20 JAR file, despite being labelled v0.20 it still only contains v0.19
Viewing post in Known Issues (and bug reports)
I actually just installed OpenJDK (https://adoptopenjdk.net) and just launch the .jar directly; the issue really is that I shouldn't have to. Been reporting this issue for ages yet every release the Mac version is still broken.