redirect.html

<script>
    var redirectToApp = function () {
        setTimeout(function appNotInstalled() {
            window.location.replace("[Somewhere else like your youtube ad]");
        }, 100);
        window.location.replace("[iOS App Store URL]");
    }; if (/iPad|iPhone|iPod/.test(navigator.userAgent)) {
        window.location.replace("[iOS App Store URL]");
    } else if (/android/i.test(navigator.userAgent)) {
        window.location.replace("[Android Play Store URL]");
    }
</script>