Plugged a Bluetooth USB to Tablet but seems not working
Most tablets that comes with the Bluetooth share app installed, and have a Bluetooth option in Settings, while not having a built-in bluetooth, typically indicates support for such dongles.

I have used generic Android TV Box (CDR-King brand) with no bluetooth built-in but has a menu for it. Plugging a bluetooth dongle to a usb port activated it. Based on this, your tablet's ROM does not support bluetooth. My advice is to root it, and flash a custom ROM with bluetooth support if applicable.