No Jan, this addon must be installed additionally. Download the addon again from the server and look in the local readme file for more detailed information on integration.
And in this area we have discussions about the
Preview Addon. There you will also find at the first entry the link to the download area. Look there to under the addons : Preview
I am sure that is your problem resolves quickly. Well ... I hope so ;-)
But you can just at the beginning, because you make yourself the most mistakes, let your forum also almost automatically compose via the
miniBB Compiler. Select what you want to install everything, let the Compiler work, and then download the finished package and install it.