This installation process is different from what you might use to see for other distro. It's not the traditional "boot -> mount -> install" process, so you might have a hard time with it if you're actually "noobish" as you said.

You need to create a bootable media, boot from it, then "pseudo-install" a RAM based system (initrd), boot from it, and finally install the final distro onto the SD card. This is a tedious process which rarely works on first try. I don't even think I managed to complete it even once myself (not that I'm a reference, but I consider myself an "advanced" linux user).

Anyway, good luck with it, and if you manage to get it installed, report it here! I'd love to hear more about it :)

EDIT: btw, thanks a lot for the link! I was convinced crux was x86 only. That's a good news!