Hi, Just click on the group icon in the top and another click on a group. If its join-able you should se a button called Join Group. If its private you need to send a pm to the group admin to invite you
It should work, but I would just do a fresh install on the new machine, you'll need to install the dependent programs anyway, and the rest of the install is fairly painless. After that, you can just copy your changed files and/or database dump.
After your friendly replies i would like to give an update. I did play with phpbb and its really nothing to go these days. It feels like stepping 20 years back compared to the nodeBB user experience.
What i am doing now is to refactor my game on base of angular2 stack and to add a a very small forum like messaging feature myself. I think this will be the best solution because it seamingless fits into my application.
You are doing a great job here and if i ever search for a real forum again i will come back 🙂