Been AGES since I messed with Ubuntu
there are requirements that need to be met (further down on the Calibre Linux download page)
Code:
You must have xdg-utils, wget, xz-utils and python ≥ 2.6 installed on your system before running the installer.
You need GLIBC 2.18 or higher and libstdc++.so.6.0.21 (from gcc 5.4.0) or higher to run calibre
I think the second one is your problem. Launch the Package manager and see if there is that version (or above) available