I wanted to find an easier way (or a way to begin with) to update games, so I decided to download the itch.io app. I used the MacOS link, and I ended up downloading a 'disk image'. It tells me that I can't open it because there are 'no mountable file systems'. So I tried the presumably built-in tool for these files, and I received the same message.

Any help would be greatly appreciated, as I don't know what the hell I'm doing. I've picked up on some things over the years, but I've never encountered anything like this. Thanks, and be well.