Hi there,
I’m really sorry that you’re going under this situation but our theme supports PHP version 5.6 and above. So this issue is happening because you’re may be using PHP version 5.5 or lower. Please upgrade your PHP version from your hosting so that you can run our theme with ease. Also upgrading the PHP version to latest which is 7.2 would make your site faster also will be stronger in site hacking. Please do so & let me know if you’re still having issue with the addon.
If you’re unable to upgrade PHP version you may want to contact with your hosting admin or may be we can help if you can provide the cpanel access in a private comment.