simplesamlphp upgrade from 1.19.1 to 1.19.6 is giving issue

Recently simplesamlphp has been upgraded to 1.19.6 from 1.19.1, we placed all needed certs, metadata, config files and applied all folder permissions and it is not working at all. after entering login credentials site is giving following error.

Warning: require_once(/www/proj/simplesaml/lib/_autoload.php): failed to open stream: Permission denied in /www/proj/html/wp-content/plugins/wp-saml-auth/inc/class-wp-saml-auth.php on line 89

Fatal error: require_once(): Failed opening required '/www/proj/simplesaml/lib/_autoload.php' (include_path='.:/usr/share/pear:/usr/share/php') in /www/proj/html/wp-content/plugins/wp-saml-auth/inc/class-wp-saml-auth.php on line 89
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Also when I tried to open sites simplesaml/ page it is giving 403 forbidden access error.