Hi Josh,
Oh, I didn’t notice that you created a separate thread at first and answered you here.
As @snillor999 said, Emlid Caster can be used when your base is set on a point with known coordinates, for example. In this case, with the caster, you can pass the corrections to the rover via the internet and achieve absolute accuracy.
But to place the base via NTRIP, you need to get corrections from NTRIP Service (CORS).