Administrator Help article is missing key information: Set up a RED device automatically (turn on RED provisioning service)...

URL: https://docs.sophos.com/nsg/sophos-firewall/19.5/Help/en-us/webhelp/onlinehelp/AdministratorHelp/Network/Interfaces/REDInterfaces/HowToArticles/REDSetupAutomatically/index.html

First section identifies step one, as follows:

How automatic provisioning works

Here's how the provisioning server sets up a RED tunnel with the firewall:

1. You turn on the RED provisioning service in the firewall."

Then objectives misses the first step, identified above and therefore the instructions for the configuration step is missing from the rest of the document:

Objectives

To set up a RED device automatically, do as follows:

1. Add a custom zone for RED devices.
2. Add a RED interface.
3. Create a firewall rule for tunnel traffic.