¿Cómo instalar Python en MacOS Catalina usando homebrew?

Estoy intentando instalar Python 3 en MacOS Catalina (10.15.3 (19D76)) usando homebrew pero da el siguiente error:

dmanna-a01:operations dmanna$ brew install python3
==> Downloading https://homebrew.bintray.com/bottles/python-3.7.6_1.catalina.bottle.tar.gz
Already downloaded: /Users/dmanna/Library/Caches/Homebrew/downloads/d5d5e7ec237016a2c35d66ddbe2edfa461d9fa20da5cad2ad3ffeb08f6d87bae--python-3.7.6_1.catalina.bottle.tar.gz
==> Pouring python-3.7.6_1.catalina.bottle.tar.gz
Error: An unexpected error occurred during the `brew link` step
The formula built, but is not symlinked into /usr/local
Permission denied @ dir_s_mkdir - /usr/local/Frameworks
Error: Permission denied @ dir_s_mkdir - /usr/local/Frameworks

Versión de cerveza

dmanna-a01:operations dmanna$ brew -v
Homebrew 2.2.5
Homebrew/homebrew-core (git revision 028f1; last commit 2020-02-10)