Plugin can't be activated because of a fatal error

[WebworkrNet]

WordPress 4.9.8 Plugin Version 0.1.1 Das Plugin kann nicht aktiviert werden, da es einen fatalen Fehler erzeugt.

Warning: require(.../wp-content/plugins/bookmark-manager-master/vendor/autoload.php): failed to open stream: No such file or directory in /www/htdocs/w0147f9a/bookmarkmanager/wp-content/plugins/bookmark-manager-master/bookmark-manager.php on line 38