When a free pattern is supplied by a yarn company, the whole point is to sell that particular yarn:) . So they list a particular yarn. But if you don't want to use it, or can't find it, you just match the gauge. A very helpful site is www.yarndex.com. You look up the yarn listed in the pattern, and they give you details, which you can then use to find similar yarns. On a yarn label, there will be a little drawing of a skein of yarn with a number in it. You want a number 5 for this pattern. But those numbers cover a range of thicknesses, so just make sure the gauge they suggest-- a small square with X sts on one side an X r on the other. Don't worry too much about the r number; those are how many rows equal 10cm and that's not as important as the sts number, which is how many stitches in 10cm, and that is crucial. You're looking for 14, and if it's slightly different, say, 13 or 15, you'll be able to make it 14 sts by going up or down needle sizes. But if it says 10 or 18, I wouldn't use that yarn-- the result will be a fabric which is too stiff or too loose.
I'm wondering if your difficulty with the pattern is that they give a lot of info before even beginning the pattern? There are all sorts of special pattern sts, wrap info, etc., and that's just to explain what will be in the pattern, itself.