A quick guide of what worked for me.
Geth is the official implementation that allows you to run an Ethereum node. There are several others.
I installed it with Homebrew based on the official geth guide for macOS.
Homebrew installation:
$ su admin
$ /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
Geth installation:
$ su admin
$ brew tap ethereum/ethereum
$ brew install ethereum
Verify (as regular user):
$ geth
- wait for message "Starting P2P networking"
- interrupt (Ctrl-C)
- check that there are no obvious errors