There's no global-rainbow-delimiters-mode anymore. It used to exist, but it was impossible to keep it from breaking some major modes. It's strongly recommended to use major mode hooks instead, as shown above. There's nothing stopping you from defining global-rainbow-delimiters-mode yourself, but if it breaks something, you're on your own.
Per https://github.com/Fanael/rainbow-delimiters#global-mode: