To easily install Crystal on Mac you can use Homebrew.
brew update brew install crystal
If you get an error like:
ld: library not found for -levent
you need to reinstall the command line tools and then select the default active toolchain:
$ xcode-select --install $ xcode-select --switch /Library/Developer/CommandLineTools
To the extent possible under law, the persons who contributed to this workhave waived
all copyright and related or neighboring rights to this workby associating CC0 with it.
https://crystal-lang.org/docs/installation/on_mac_osx_using_homebrew.html