The crown race is a small washer type piece of metal that is fitted down around the steering tube (sits at the base where the fork starts) - this should only be a couple of bucks and the shop will have them if you're having the fork installed at a shop. Even if you want to do this diy, you'd also need to have a star nut installed inside the tube as well.
Unfortunately it looks like the Juggernaut is a tapered head tube (look at the steer tube, it is slightly bulged at the bottom vs the top), so a straight steer fork won't work on the juggernaut frame.