This is an Application Stub for macOS Catalina and newer to run Logisim without installing the old Java Runtime Environment.
Logisim requires the Java JDK. I recommend installing it with Homebrew. After installing Homebrew, download and install Java as a brew cask in your Terminal:
$ brew cask install java
Alternatively, if you are running macOS 11 (Big Sur) and HomeBrew > 2.6.0:
$ brew install --cask adoptopenjdk/openjdk/adoptopenjdk8
Next, download the Release-App and drag it into your Applications folder.
I didn't develop the Logisim app! This is only an Application Stub to run it on macOS Catalina and newer. Credit: http://www.cburch.com/logisim/index.html