Paid Memberships Pro - Multisite Redirect

pmpro-ms-redirect.php

<?php
function pmpro_multisite_subsite_custom_redirect() {
	if ( is_main_site() || is_admin() ) {
		return;
	}
	if ( function_exists( 'pmpro_hasMembershipLevel' ) ) {
		global $current_user;
		if ( 0 == $current_user->ID || ! pmpro_hasMembershipLevel() ) {
			wp_redirect( get_site_url( 1, '/membership-account/membership-levels/' ) ); // Assume main site ID is 1.
			exit;
		}
	}
}
add_action( 'template_redirect', 'pmpro_multisite_subsite_custom_redirect' );