So door is the oblong with string running up from it over motor and then off to counterweight on left,
with two small plastic channels either side to carry the door
(it drops into a third at base to make it 'lift proof'
actually here's a more detailed version showing the travel adjustable...
Or like I did,
an automatic curtain closer,
motor mounted on a short slide for adjustment, has two stop settings no top for open/close
apply power it runs either one way or the other, I either control mine with a simple plug in timer>AC adaptor>motor
or a cheap remote controlled plug in thing...