Really annoyed that the rally DLC never went on sale. Or if it did, I completely missed it.
I think the season pass was half off just a couple weeks ago, if that makes you feel better... (edit: whelp nope it wasn't half off, it was 75 percent off mid-september)
It includes the rally expansion.
Also, downloading everything was a real tedious thing on Xbox One. I had to initiate the download in game, then it'd spit up a message, then it would show up in my ready to install list under manage game. At least I got them all there now, but damn. I think there was an equally "weird" process when I was downloading everything for the Gears of War 3 season pass (although, it was a lot less things I had to deal with there.)
Had the same problem when downloading the free (!) stuff. It said my credit card info cannot be found. I have never added my cc details to my xbl account and bought everything with points back then.
Anyway, try clicking purchase several times. For me the error occurred like 3 times and then it worked. Very weird.
Yeah, I get this error sometimes too. It seems to happen more often with free stuff for some reason. Usually I just have to retry a few times and it'll work.