Trying to Install RMarkdown Package Error

[andresrcs]

This is a macOS specific issue, try the solution described on this related thread.

You can't install the software because it's not available on the software update server

I ended up removing my current command line tools in terminal: sudo rm -rf /Library/Developer/CommandLineTools then I downloaded an older version of the command line tools since git was my main problem and it no longer runs on OSX 10.15. (https://github.com/Homebrew/homebrew-core/issues/52490) I did this by going to https://developer.apple.com/download/more/ and downloading Command Line Tools 11.3.1! It works now. Not a permanent fix, but helped.