@iostrym
Have you rebooted your Synology?
For me that solved similar problems with DSM 5.
If this does not work then
- put a small (calibre) test database in a directory "ebook" in the "cops" directory
- change the relevant line in config_local.php to $config['calibre_directory'] = './ebook/';
- maybe add the cops directory to the open_basedir (not really sure if this is needed / can't remember if I ever did )
- maybe reboot and try again
http://192.168.1.50/cops/checkconfig.php
Now cops should work ....... if not we can continue trouble shooting.