Hi there! I understand that you're able to use the FitOn app on your phone but are having trouble logging in on your laptop. I'd be happy to help sort this out. To get started, could you please tell me:

1. Are you using the FitOn web app on your laptop or did you install a desktop app?
2. What exactly happens when you try to log in? For example, do you see an error message or does the screen just stay blank?
3. Have you already tried anything like clearing your browser cache or restarting the browser?

Knowing this will help me guide you better. Meanwhile, here’s a general approach we can try:

### Step 1: Clear Browser Cache and Cookies
Since you're on Windows 10 and using a WebKit browser (likely Edge or Safari-like), cached data might cause login problems. Try clearing your browser cache and cookies:
- Go to your browser settings.
- Find the privacy or history section.
- Choose to clear browsing data, selecting cookies and cached files.
- Restart your browser and try logging in again.

### Step 2: Try Incognito/Private Browsing Mode
Sometimes browser extensions or stored data cause conflicts. Open a private browsing window (Incognito mode in Chrome/Edge) and attempt to log in from there. This disables extensions and uses a fresh session.

### Step 3: Check Internet Connection and Firewall Settings
Ensure your network connection is stable because login requires server communication. Also, verify that firewall or antivirus software isn’t blocking FitOn’s website or login services.

### Step 4: Reset Password (if relevant)
If the issue involves password errors, you might want to reset your password via the "Forgot password?" link on the login page.

If these steps don’t solve it, let me know what you observed during each step, and we can dive into more specific fixes related to account synchronization or browser compatibility.

Does this sound good to start with? Any extra info you provide will help me assist you faster!