Hi there! I understand you're having trouble linking Doomsday Last Survivors to the Facebook third-party app. Let’s work through this together. Could you please tell me what exactly happens when you try to link your Facebook account? For example, do you get an error message, or does the linking just not complete?

While you provide that, I’ll start by sharing some common and effective steps to resolve this kind of issue on your Windows 10 system:

1. Check Your Internet Connection:
Ensure your internet is stable and working properly, as connection issues can interrupt the linking process.

2. Clear Your Browser Cache:
Since Facebook linking often opens a browser window or uses a built-in web view, clearing your browser cache might help. In Windows 10, this can be done in browsers like Chrome, Edge, or Firefox through their settings under Privacy → Clear Browsing Data. Clear cache and cookies, then restart the browser.

3. Verify Facebook Login Details:
Make sure you are logged into the correct Facebook account both in the browser and any installed Facebook app on your device.

4. Allow Facebook Permissions:
Check that Facebook has permission to allow third-party apps to connect. You can do this by:
- Going to your Facebook settings page (on the web)
- Navigating to “Apps and Websites”
- Ensuring Doomsday Last Survivors is listed and allowed to access your Facebook account.

5. Try Linking from the Game Settings:
Open Doomsday Last Survivors, go to the Settings menu, find the Connect button, and try linking your Facebook account from there.

6. Update the Game and Facebook App:
Ensure both are updated to their latest versions to avoid compatibility issues.

If you have already tried these, please let me know which ones so I can guide you with the next steps or deeper troubleshooting. Also, is there a specific error message you see or does nothing happen? That info will help a lot.

Looking forward to your details!

Are you satisfied with these initial instructions so far?