Hi there! Thanks for reaching out. I understand you're trying to log in to the Pizza Hut app on your Windows device but it only lets you sign up instead of logging in. Let's get this sorted out.

To start, could you confirm a couple of things for me? Are you using the Pizza Hut website through your WebKit browser or the app installed on your device? Also, have you tried using the "Forgot Password" option in case the login button is hidden until you enter your credentials?

In the meantime, here are some steps to try:

1. Clear your browser cache and cookies: Sometimes stored data can cause login issues.
- In your WebKit browser, press Ctrl+Shift+Delete to open the clear browsing data menu.
- Select cookies and cached files, then clear.

2. Refresh the page and try again.

3. If that doesn't work, try accessing the login page via a direct URL (like pizzahut.com/login) instead of the sign-up page and see if the login form shows.

4. Double-check you are using the correct username/email and password combination.

If you've already tried these or the problem persists, let me know, and we'll dig deeper!