Today, I surfed in google about forum softwares. There are plenty of results talking about them both opensource and non-opensource. Until now, I tested some forum softwares like phpBB, SMF, Simpleboard… I had a look at the feature MyBB has. Truely, it has some special features which are not available in SMF I am using.
It did not take more than 5mn to get MyBB up 
. The installation of each forum is not so far different – uploading files, create database (mostly MySQL), then run installation wizard.
Take a look the installation I just did about a few minutes ago here.
. They are using Discuz! Forum. I have never installed such forum software before. I guess, it’s not bad and might have some features which other opensource/free forums do not have. That could be the reason why the webmaster chose it.