Thanks for the reply.
I had misunderstanding how this plugin works, now I got it.
It works now 🙂
Just for other users if they see this topic in the future: You should go to each Category you created before or create after that, click on Subscribe green button and the plugin should work for you like me.
For example in my website I have 3 categories called Q/A, Free Discussion and Announcements. I should subscribe in all these three and then just wait for another user to create topic.
I haven't been around for a while. Life has been busy. I moved and got a new job. Then I saw my favorite Linux Distro (Antergos) changed their forum over to NodeBB. So I had to come check it out. Things are really starting to look solid around here!