/usr/lib/x86_64-linux-gnu/libowncloudsync.so is in libowncloudsync-dev 2.4.1+dfsg-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libowncloudsync.so.0
/usr/lib/x86_64-linux-gnu/libowncloudsync.so.0