I'd advise you to delete this post.
There could be a legit reason to install with app sync, for example, I have an app that was purged from the App Store, due to not being updated in years, and the developer's email and website has been gone for years. I can no longer install that app, that I paid for many years ago....It does still function, and that is not currently an equivalent replacement. It was called VideoStampTime...
But, lets put that aside, and just point out that AppSync is not currently working, and if you want to use it for whatever purpose, you will just have to wait for it to be updated. Keep an eye on Karen's Pineapple, as Karen is the one that usually updates it.