When you access the Sage 200c help files the web pages relate to the latest of 200c. So a user running Sage 200c Summer 2017 will see the same help files as a user running Sage 200c Summer 2019. As there are features that are present in the later release that were not in the earlier this can result in misleading information being shown.

For example the way the Web App is configured for external usage changed in the Sage 200c Summer 2019 release, and this is what is documented in the help files - http://desktophelp.sage.co.uk/sage200/professional/Content/General/Contacts%20setup%20365.htm#Connect. In earlier 200c releases you still had to use external facing web certificates which is both completely different in method and comes at a potential cost to the client.