This great add-on works sometimes unfortunally here. I now have have document tahts is light, but takes ages to upload. I've encountered this many many times with other documents. Usually when restarting my laptop or Adobe this solves the problem. Not now.
My internet connection is blazzingly fast, clearly an Adobe error. Badly programmed? So lets stick to old fashioend sending pdf-s, because this seems to be a beginners step for Adobe.