I can't get OptiFine HD to open its installer. Every time I try, the file just gets unzipped. Necessary details: MacOS Catalina. I tried the Magic Launcher method, but Magic Launcher does not have a new enough version for Minecraft 1.16.3 and when I tried anyway MacOS responded with "“MagicLauncher.app” needs to be updated". I am not sure what to do. I would rather not try Forge because I have done it before and after a year of use eventually broke the entire .jar file. Luckily, I was able get the Minecraft folder out before deleting and reinstalling, so no worlds lost.
My only guess would be that I do not have Java installed. The Java Version of Minecraft does not need Java installed as it has its own Virtual Java.