sims 4 won't open, installed on external hard drive

I have downloaded sims 4 to my external hard drive (I use Mac book pro 2020 to play) but it won't open, it only pops up in the bar but then closes after a few seconds. It has worked before but then suddenly stopped working... I have uninstalled and installed it again multiple times on my hard drive and still wont work. What can be stopping it from working?? I see someone saying that having put everything in game to high (game graphics ect) can have something to do with it? I did that but have re-installed it multiple times after that. I have also tried repairing it multiple times also.