Creating Levels and environments in Unity using Probuilder

How to install and use the core features of ProBuilder in Unity to quickly prototype[1] / grey box a level.

Terms definitions
1. prototype. Prototyping is the modelling of a realised but yet-to-be-implemented technological outcome. The purpose of prototyping is to evaluate the fitness for purpose of a technological outcome against the brief and is undertaken to establish (or not) a defendable case for its implementation, refinement or further development.