IT LOOKS GREAT! (somehow the mac version isn't working for me 😭)
1. right click the app and click "show package contents"
2. navigate as follows: Contents>MacOS
3. you'll see a file called "SUBTERBALDI"
4. Open mac terminal and type "chmod +x "
5. drag the SUBTERBALDI file into the terminal window. It should automatically type out the full directory for you. (IMPORTANT!! Make sure there's a space between the directory and "+x"
6. Press enter in the terminal window then close out of terminal
If you did everything correctly the icon for the SUBTERBALDI file should have changed from the default document icon to one that says "exec"
7. go back to the app called "Substitute" and then double click it. It may not work the first time so right click it or control+left click it and press "open"
God damn it apple