Unable to open files

Hi,
I have several mscz files that were created by my piano teacher. In the past, I was able to open them in musescore. I recently got a new computer and had to download the app. after installing, I click on one of the files, Musescore opens, but it does not open the file. So here are my questions:
1. Is there a way to open these files?
2. Do I now need a subscription to use the program to open previously created files?

Thanks