If you come across the following error message while using PowerPack’s Header and Footer option then it means that the theme you’re using is not supported by default.
But there is no need to worry because you can add the support for PowerPack’s Header / Footer by adding the following code in your current theme’s functions.php file.
add_theme_support( 'pp-header-footer', array( 'header_hook' => 'current_theme_header_hook', 'footer_hook' => 'current_theme_footer_hook', ) );
current_theme_footer_hook should be replaced by actual hooks present in the theme. These hooks are responsible to render header and footer. If you’re unable to find them then please contact the theme developer to get the correct hooks.