Check that ACF included in your theme, if not than include acf. Try to use following code:
if( !class_exists('Acf') )
include_once get_stylesheet_directory_uri() . '/advanced-custom-fields/acf.php' );
Check that ACF included in your theme, if not than include acf. Try to use following code:
if( !class_exists('Acf') )
include_once get_stylesheet_directory_uri() . '/advanced-custom-fields/acf.php' );