A THREAD FOR NEWCOMERS!

Hello everyone! Please excuse my noobishness; I'm about to ask some silly questions, but I really need answers. It made me nostalgic and I want to play Heroes 3 on my laptop. The problem is, I have a MacBook, but at least it's not an Air, so it works. Here's my question for everyone: Can anyone suggest where to download a reliable version for macOS? I need one that at least works and allows me to play the campaigns from Armageddon's Blade or something similar. And a question that's almost science fiction: Is it really possible to play online on a Mac? Thank you in advance for your honest answers!