Please provide an admin account so i can help you check the issue.
Before do it, please be sure your server environment meet our requirements as article bellow to make the theme functions work:
Would you mind providing us with Wordpress login credentials so we can take a closer look?
That is just warning message of php structure. Don't worry, it does not effect on theme functions.
If it display on front page, you can hide it by turn debug off.
define( 'WP_DEBUG', false );
@ini_set( 'display_errors', 0 );
The following code, inserted in your wp-config.php file.