I have also tried Android Studio Emulator, hoping that it would be able to work, and would make the development easier, as the app is supposed to be installed on tablets, and the small screen of the AI2 emulate does not fit most of the designer controls.
The companion app on my phone or on the tablet works fine, but it does get disconnected quite frequently, if not touched.
Any help in getting an emulator to be able to work as a real phone or tablet, with extensions?
An emulator is an emulator (a piece of software running on non Android hardware). It has neither the hardware or sometimes software to mimic a real advanced or modern Android device.
The emulator that is set up with aiStarter is very basic. It mimics I believe an Android 4.0 or so. Extensions that use Android system features higher than about 4.0 will fail along with those that cannot mimic required hardware (sensors, gps etc..)
There are fancier emulators... search for GenyMotion etc. and you will get additional features; however in most instances they won't emulator hardware.
Borrow an older phone that no longer has a contract; then use it with Companion on WIFI instead of an emulator.