You need to first use the Crop Tool in Lightroom to produce an image that is the aspect ratio of 1100x530
Then you can export with the Image Size set to 1100x530 and then you should find the exported image is the desired size.
You must crop it first to 11:3 before exporting it. Your vertical height on your image is too tall in relation to the horizontal width. Short of distorting the image wildly there is no way to take an 11:5.3 peg and force it to fit into an 11:3 hole.
Then when you export it set it so that the Long Edge is 1100 Pixels.
Some confusion in the 3 posts
Original post said two different sizes; perhaps one was a typo; it said in one place 1100x530 in one case my answer is correct; it also said 1100x300 in which case Rikk's answer is correct
the other solution is that none of the values are correct...
I typoed the last one... the image I need to export is 1100 by 530....
I think I see the solution....crop first