Not able to open latest version of Musescore on Mac

I downloaded the latest version of Musescore, but I wasn't able to open it. I even uninstalled, redownloaded, and tried to reopen it, but I got the same message. Something along the lines of "could not check this for viruses, so check with the software developer". Anyone else having this issue, or have a workaround? I tried downloading version 2 instead, but of course it won't open the .mscz file I have because it was made with the newer version...

Any help or advice appreciated - thanks.