Hmm, the pad layout on this one is slightly different than that of the version that adafruit is selling. I suspect that you would need to select your supplier of choice and get their suggested pcb layout to make a proper pcb. I would have though that a 2020 was a standard footprint, but I know very little about smd parts. Perhaps one of our smd experts will comment? As noted before if you start with the 5050 footprint available in core I don't think that will be too difficult a task. All you need to do is reduce the size of the pads (and possibly in this particular case add two pads in the center for gnd and vcc it looks like) which shouldn't be that hard once you identify the package you need of course 
. As I recall, the person that posted the data sheet made similar posts to several threads and I expect (but don't know ) got deleted as spam as it was nothing to do with Frtizing directly just the data sheets.
Peter