widget url 404'ing

I'm creating a widget for the first time. When I grab the url from the base url section of the widget builder and append /widget.html it 404's

Just wrote a very basic test. I have a folder structure

app.zip

- widget.html

--js/app.js

/widget.html

<!DOCTYPE html>
<html>
<head>
    <title>Basic Modal Test</title>
    <script src="https://live.zwidgets.com/js-sdk/1.0.5/ZohoEmbededAppSDK.min.js"></script>
    <script src="js/app.js"></script>
    <style>
        body { font-family: Arial; padding: 20px; text-align: center; }
        button { padding: 10px 20px; }
    </style>
</head>
<body>
    <h3>Modal is Working!</h3>
    <p>This is a basic test modal.</p>
    <button id="closeBtn">Close</button>
</body>
</html>

/js/app.js

ZOHO.embeddedApp.on("PageLoad", function(entity) {
    console.log("PageLoad triggered - Modal opened with entity:", entity);

    document.getElementById("closeBtn").onclick = function() {
        console.log("Close button clicked");
        ZOHO.CRM.UI.Popup.closeReload({ Entity: "Sold_Leads" });
    };
});

ZOHO.embeddedApp.init();
console.log("App initialized");