The checkbox next to the feed name should be ticked for the feed to be enabled and be automatically checked for new items.
When a feed is added, it will only pick up new items and not anything already in the RSS feed unless you press "Force Download".

  Name Feed URLs  
UFC
https://api.nzbgeek.info/rss?t=5060&limit=200&dl=1&r=eAcQmR1YSdbOUoaoyIp9JUx0QaKdiN4b

  Next scan at: 03:22 Checking interval (in minutes, at least 15). Not active when you use the Scheduler!