Davis Before uploading to the server, we have to check if it is working properly on localhost. I have tested on Apache, Light server without any problem. I also tested it on some FREE HOSTING SERVERS, yeah it worked. It is beta so it can't be used for commercial purpose, just taste it. Me to installed flarum only for testing.
I'm agree uninstalling Ubuntu may create problem if we want to install extensions or want to do other things. That's why I said to use VM ( Vmware or VirtualBox ) ?