APK files are for Android. http://www.samsung.com/us/video/tvs/UN65J630DAFXZA makes no mention this is an Android TV.
As to the missing Samsung apps, it's very new so make the call to Samsung to fix that part of the issue.
Hello everyone, i just recently bought this 65inch Samsung TV UN65J630DAFXZA and i only have the smart hub and no Samsung apps application. I'm currently on the latest firmware. Another question is, why can't i install Aptoide for TV or other apk files. Anyone knows any good tricks to maximize my use of this tv like free channels and such. Thank you