Update, Sep 17: I’ve just submitted new version with this issue fixed, it’s in “Waiting for review” state now
I must apologize to Audiobook Binder users I did a sloppy job on releasing version 1.17. While fixing one bug I introduced another one. It does not affect new users only those who upgrade AppStore build from previous version. The bug manifests itself as “Can’t create output file” message immediately after pressing “Bind” button. The workaround is to change destination folder to anything but the current one (e.g. Music). It should fix the issue and after that you can change it back to previous location.
I’m working on a fix and will release it ASAP.