Change required capability for themes menu.From https://wordpress.org/support/topic/one-free-theme-no-more-included-or-it-is-error-as-theme-sub-menu-not-showing?replies=2#post-6079513

functions.php

<?php

// Copy everything below here to your functions.php file.
add_filter('emodal_admin_submenu_themes_capability', 'fix_my_emodal_theme_menu');
function emodal_admin_submenu_themes_capability($capability) {
    return 'edit_posts';
};