Error when using nicepage template in joomla v3.9.3

Hi,
I'v create a template in nicepage and installed it on a joomla site (v3.9.3). I'v imported the template content via to import data option of nivepage, but when i want to use the template I get an error.

Warning: require_once(D:\wamp64\www\ecgroep\templates\ecgroep/library/Core.php): failed to open stream: No such file or directory in D:\wamp64\www\ecgroep\templates\ecgroep\functions.php on line 9

Fatal error: require_once(): Failed opening required 'D:\wamp64\www\ecgroep\templates\ecgroep/library/Core.php' (include_path='.;C:\php\pear') in D:\wamp64\www\ecgroep\templates\ecgroep\functions.php on line 9

Any suggestion on who i can resolve this ?
grt,
Maarten