Not knowing the setup. You could either:
1) Use the inbuilt password protection within WP and hope your theme caters for this OR
2) You need to create a custom template:
<?php
/**
* Template Name: Password-Protected Custom Template
*/
?>
<?php get_header(); ?>
<div class="entry-content">
<?php
// STARTS - wrapp your content with this conditional statement
if ( post_password_required() ) :
// if your post is password protected with our Pro version, show our password form instead
echo get_the_password_form();
/* display the password protected content if the correct password is entered */
else :
// display any custom private content
echo 'custom HTML content';
// fetch & print WordPress custom field value via get_post_meta calls
$custom_field_content = get_post_meta( $post->ID, 'key_1', true );
echo $custom_field_content;
// fetch & print ACF fields
the_field( 'acf_introduction_text' );
endif;
// ENDS - hide custom fields with PPWP password protection
?>
</div>
<?php get_footer();?>
You can then assign the template to your page and set the password.
