Installation on iMac fails

Hi,
I am a brand new user trying to install Home Assistant on my Imac to investigate the possibilities for my family. I followed the instructions on your web page …

… but they are very out of date. I installed Python 3.7.3 (64 bit), but did not install the tools (as instructed by the video). When running the Terminal code “hass —open-ui”, several modules are reported as missing and the installation fails.

I am running Mac High Sierra, 10.13.6.

Does any one have updated instructions?