Unable to download musescore.3 onto a mac book pro.

I had difficulty doing this a month ago and today came back to see if there would be any difference, unfortunately not.

I can download it onto my mac but then cannot open I when downloaded as my computer says that it can't be opened because of it cant check for malicious software. I'm unsure what the problem is. If anyone has encountered this problem or knows how to fix it help would be appreciated.