I completed my online application Friday, the 19th, and can report that the IHS payment portion of the process is still very buggy. I got different error messages about the system being unavailable, and couldn't move forward, despite trying a number of tricks (logging off/logging on, restarting browser & computer, switching browsers, waiting a couple of hours)
What eventually seemed to work was clearing the cookies in my browser and logging into the application again. (I also did switch from my usual browser, Chrome, to Safari, just because I didn't want to lose my Chrome data.) I was finally able to complete everything.
By the way, when I was using the IHS portion, it had the label "ALPHA", which is worrying, because the alpha version of a software release is meant for internal testing, and even the next version, the beta, is not meant for general release.
So, it's hard to know what's going with this not-ready-for-primetime application, but I'd encourage anyone who has trouble to send feedback through the links in the application in hopes that the technical people can get it working right!