heavy door can I use it?

It depends what you intend to hang it on and a picture paints a thousand words if you can get one of the gate and the post.

You could obtain a heavy duty 8 foot x 4 inch sq. wooden fencing stob/post, hammer that into the ground with a fencing maul (or sledgehammer at a push if you can't get hold of a maul), then hang your "gate" off that.