/usr/lib/x86_64-linux-gnu/libQt53DQuick.so.5 is in libqt53dquick5 5.5.1-4ubuntu3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libQt53DQuick.so.5.5.1
/usr/lib/x86_64-linux-gnu/libQt53DQuick.so.5.5.1