Success! Here's my thoughts so far. All comments below are using my Tab S.
I was confused when the screen showing folders I could connect to showed the Calibre folders with a check mark. I couldn't tell if I needed to uncheck the ones I didn't want and of course that's what I tried to do first.
I should have realized that you can only connect to one at a time. I don't know if anyone else would be confused about this or not.
I went to settings and reset cloud connection, but after connecting was shown a blank screen. After disconnecting and reconnecting again the screen displayed properly.
I got a message that the book could not be saved to device memory. I have Kitkat 4.4.2 and have my books set up to save on the sd card. I am rooted.
Is it possible to show which library you are connected to somewhere? Maybe the upper left where it now shows 'CC Cloud'?
Is it possible to show a count of how many books are in each category?
I like the 'on device' category. I keep all books on my device, so this is an easy way to see what's missing.
I like the way the settings are now condensed, but I think a change is needed to allow me to view the settings while connected, but not change them. I wanted to check where my books are saved to, but I couldn't because I was connected.