I downloaded a software from the internet which is in .arc format. How can I extract the files on MAC?
The arc file is 4GB, but I believe it will be 30 GB when extracted.
Take a look at ARC File Extension for different file formats with the .arc suffix.
The Unarchiver has been acquired by MacPaw and is available for free download. I just downloaded it and used it to successfully unarchive an ARC archive from 1988. I'm running it on macOS High Sierra (v10.13.5), but it should run on anything since macOS 10.7--and MacPaw even has legacy versions available. The Unarchiver lists 60 different archive formats in its preferences.