Don't worry, the exact same thing happened to me. I pre-ordered it, and I had the option to download it, but no matter how many times I tried it would always say "download failed" after about a half hour of trying I checked the pre-order and it still said processing and I hadn't been charged yet, I cancelled the pre-order and just bought the digital copy of origin there and then, I would advise to do the same, don't worry nothing will happen, just click cancel and go back into the origin store and it will give you the option to buy it, did that and it downloaded straight away, hope I helped. :)
