1) If you can't see .circ files on Mac, follow these steps:
Press Command + Shift + H
This should open your home folder (the folder should be named after you or your username)
Drag the .circ file into this folder
Logisim should now be able to see the file
Also, make sure the filename ends with “.circ” rather than “.circ.someting_else”. Ensure Logisim has been granted permission to access the folder in which the file is placed.
2) If you can't install Logisim:
Instead of downloading the executable, try using the .jar file (https://sourceforge.net/projects/circuit/files/2.7.x/2.7.1/logisim-generic-2.7.1.jar/download). Then you can run it by typing
java -jar logisim-generic-2.7.1.jar
To be updated throughout term with other common issues.