Can Android phones upload media via Firefox on Ubuntu Mate?

I was out with a friend this morning and got some good photos on my phone using Android. I thought I'd share them on Facebook, so I opened Facebook on Ubuntu Mate PC, in the Firefox web-browser, clicked "What's on your mind?" and there was a prompt to upload media from Mobile Device. However, when I clicked on that the "gear box" icon just turned and turned perpetually.

Do I need to run a "Virtualized Android x86 for PC", as I read about in another post?

Thanks in advance,
Jason