I do not know where you can download the songs--perhaps the Filthful and Disgraceful Slavebugger is trying to force people to pick up the CDs, where they can be guilted into donating for them. Or, they are trying to restrict access to certain versions of the songs. I remember when I first joined the cancer, I wanted the full-orchestra versions as individual songs--all I could get was full-orchestra versions as medleys on tapes, and individual songs as piano on records. Not what I wanted--and they wonder why I didn't get rid of my worldly records.
Availability is one thing. Quality of the recordings, performances, and the "music(??)" is another. From what I have heard, those songs are atrocious. I advise searching through this board through threads about how wretched most of the songs are--a waste of hard drive space, sounding like dying cats and cult chants, and not being able to sing them correctly. If you have heard them and still want them, you are probably (no, I will not stake your life on it) going to have to pick up the CDs at the Kingdumb Hell or borrow them from someone you know that has them. At which point, you can rip them onto your computer as MP3 files, and then do as you please with those files.