I finally managed to connect it. The seller replied to my question with the following instructions:
So please kindly try to use your mouse as our instruction below :
1. installed the batteries
2.open the small "turn on " button on the bottom (right) of the mouse .
mouse will be in red light .
3. press the middle scroll button and the right button at the same time for 3 seconds, then release your fingers.
4. the light on the bottom of the mouse will turn off now
4. Choose the bluetooth devise "aixunweiye" to pair the mouse with your computer.
5. Then the mouse will work well for you.