SOLVED: For anyone in the same boat that I was using MacOS!
After unzipping the Before Crisis game file, drag and place the EasyRPG Player application into that game folder and you should be good to go!
Swinging back into this comment section in case someone comes across it who knows what to do/how easyRPG works on macOS:
The EasyRPG software runs and opens perfectly on my mac! But I'm unsure how to actually install the game – or any game for that matter – into the software so I can play them haha. I can't find anything clear online to help me 😭 I can only find Windows tutorials and it's very different. Thanks in advance to anybody who helps!