How do I run a Unity build on Mac or Linux?

I just finished my project, and I want to publish it. I’m providing a version for PC, Mac, and Linux. I need to provide download instructions for each, but the problem is, I have no idea how to run a Mac or Linux build, seeing as though I’ve never used one. On PC, it’s just click on the .exe file, but I’m lost on the Mac and Linux. How do you run these builds?

They both start an app on double click too. For Linux the user might have to set “allow running as executable” or something along those lines in the files properties.