If you can't log into ancestry from FTM, what's the the specific error message you're getting? Wrong username? Wrong password?

You said you checked your Firewall, so FTM should have permission. One way to check that is to create a new tree (if you don't already have one) and go to the Places workspace and use the map feature. If it accesses Bing, then FTM is able to connect to the internet. That will be helpful to know.