When the album's finished, it'll be released on iTunes, Amazon etc. for download. Some people may want to buy it in this way and still order a story / art book and a poster / badges / t-shirts etc. We're just trying to cater for everyone really.
If a reward says that it comes with a CD, it comes with one. If it doesn't, then it doesn't.
Don't see the answer to your question? Ask the project creator directly.