You can download the nightly from here, but hopefully within a month or two there will be a full release of version 5.9. I have been watching the conversations amongst the developers, and they seem to be nearing the establishment of a release date 
In order to create the effect, I used Local Adjustments. As a primer for using LA, you should watch @Andy_Astbury1 's video. The interface is a bit hard to wrap your head around, but once it clicks its pretty straightforward.
I will try to work on a separate tutorial for lens flare and post back here, as I don’t want to highjack this thread.
Edit: The tutorial can be found here Tutorial: Using Local Adjustments to create lens flare