After you have connected both sides of the electric cable and place with plastic leading pin to the mirror housing holder spring, this picture will help you to find the right
hand position to press the mirror holder incl glass carefully to the mirror housing.
Best position to do this is if the parts are laying on the table.
Than you take the mirror assembly and hold it like into the mounting position.........this picture from KAZ is very helpful (as usual) and shows the next step.
If that job is done, you can press the mirror glass at the top side inside the mirror housing.
Now you can see and check the small metal holder, he should be hold the mirror/actuator assy.