You can no longer give access to FB directly from Elements. This was a decision made by FB a couple of years ago to prohibit access via a third-party's software interface.
It is possible to drag and drop a file from the Organizer to a Facebook post. But even here, FB seems to change the rules all the time. I post animated gifs that I create in Elements to a FB post without problems. But yesterday I attempted to post one in a reply to somebody else's post and couldn't do so from my desktop. The file seemed to land in the Reply but I then saw a never-ending message that the file was being processed with 0% completion. Since I find that posting from a desktop is different than from my phone, I emailed myself the gif and posted it from my phone. This time, the image posted but only as a still photo, not as an animated gif. I haven't investigated this any further yet, but FB's help is useless.