Set the ACF SYNC path on sage template

functions.php

<?php
add_filter('acf/settings/save_json', function($path) {
    return get_stylesheet_directory() . '/acf-json';
});

add_filter('acf/settings/load_json', function($paths) {
    unset($paths[0]);
    $paths[] = get_stylesheet_directory() . '/acf-json';

    return $paths;
});