In design 2018 on old Mac stopped working today

Hello- I have been using in design in old mac laptop with my subscription. It worked fine yeaterday and when I went to wok in my file this morning, it wouldn't let me save it. I closed in design and restarted computer and now in design won't start up at all - adore application manager just spins and spins and won't allow it to start. Computer is definitely old and can't be updated but why is this suddenly happening and is there anything I can do?

desperately need access to files today.