I can’t help you with those apps. Any questions should be posted on their threads.
AlliCrab: [iOS] Mobile AlliCrab for WaniKani
WaniKani for iOS: New iOS app
You will also find further info and instructions on how to install there. I haven’t followed the iOS apps too closely but I’m fairly sure at least one of those two was still working a few months ago (think it was allicrab, could be both). Give those threads a look. Don’t give up!