I also had problems after installing and updating every package on this thread, including qt-default, using the command line on the website, without `sudo -v` as my admin account has no password (maybe this is why my installer couldn't reach qt5 even after I'd installed it?).
Anyway, these were the lines that worked in the end - install everything mentioned on this thread (I did try with less), then run the isolated install:
sudo apt-get unstall libxcb-xinerama0 libxcb-icccm4 libxcb-image0 libxcb-keysyms1 libxcb-render-util0 libxcb-randr0 qt5-default
wget -nv -O-
https://download.calibre-ebook.com/linux-installer.sh | sh /dev/stdin install_dir=~/calibre-bin isolated=y
I defer to Kovid's opinion of course, but I would have thought an AWS Ubuntu install would be useful on the installer page? Or maybe I'm rare.