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.
I'm looking for a mid-range front suspension for my 2015 Juggernaut with a tapered headset. Can't afford the new Wren shown on the Biktrix website and have heard bad things about the generic Chinese shocks shown on Alibaba. Hoping that someone with experience has found a good solution and can share it with me. Thanks.