If it’s an aiff file, you have to do it in this order (iTunes isn’t needed at all, but I always creat a new folder with those tracks in anyway).
First, you need to open the tracks in serato, and then analyse them. Then you drag them from Serato to MiK, let it analyse, then (don’t know if you have to do this, but I always do) reanalyse again in Serato.
Now open in Engine, and update your Serato library. Once that’s done, you can then just drag them from the directory in Prime, but showing on a Serato, and I to whatever folder you want on Prime. Job done.