There is a free version? I found out that I can skirt legal issues if I create a forum that requires logging in to upload subtitles
If you just need a forum then I would recommend phpbb. However, if you are using WordPress then you are most likely going to want to search for some plugins for it such as: bbpress Buddy Press Asgaros Forum
Asgaros Forum seems much better than I expected though. But since I paid for a plugin that got deactivated without warning. Phpbb might be the better choice
if you are going to create your own site without great knowledges as coder you should do it with PHPbb