Were you able to solve this problem?
I have this problem too:
[Fri Oct 27 11:46:15.071277 2017] [:error] [pid 16969] [client] PHP Parse error: syntax error, unexpected ‘class’ (T_CLASS), expecting identifier (T_STRING) or variable (T_VARIABLE) or ‘{’ or ‘$’ in /var/www/ojs/lib/pkp/lib/vendor/slim/slim/Slim/Container.php on line 149, referer: http://domain.name/submissions
[Fri Oct 27 11:46:15.075818 2017] [:error] [pid 16990] [client] PHP Parse error: syntax error, unexpected ‘class’ (T_CLASS), expecting identifier (T_STRING) or variable (T_VARIABLE) or ‘{’ or ‘$’ in /var/www/ojs/lib/pkp/lib/vendor/slim/slim/Slim/Container.php on line 149, referer: http://domain.name/submissions
[Fri Oct 27 11:46:15.080675 2017] [:error] [pid 16860] [client] PHP Parse error: syntax error, 
unexpected ‘class’ (T_CLASS), expecting identifier (T_STRING) or variable (T_VARIABLE) or ‘{’ or ‘$’ in /var/www/ojs/lib/pkp/lib/vendor/slim/slim/Slim/Container.php on line 149, referer: http://domain.name/submissions