Hi Lee! Sorry for not getting back to you sooner!
I’ve just uploaded a new Mac build of the game. Would you mind downloading it and see if you’re able to open it? (Though I must admit I’m not super knowledgeable when it comes to Macs).
You might also try changing your System preferences to allow apps downloaded from anywhere to be opened. Though I’m not sure how advisable that would be on a school computer.
Alternatively, are you able to run the game through the Itch.io app? https://itch.io/app