The cron is automatically enabled, it's ported with the product xml
Set your settings up in the forum manager, and then try running the cron from the scheduled tasks manually to be certain your connection type is correct. If it is, it'll say Done!, if it isn't you'll get one of the errors listed in the first post of FAQs
Is that link coming up bad for a newthread, or a new reply? Or is it coming up bad for both for you?