Windows 7 Cannot signin with iTunes - Unknown error -50

I need to access some legacy apps for my iPhone 5 (IOS 10). I read where to do that I need to install iTunes version 12.6.3, which I have done. However, when I try to sign-in I get an error -50. It says this is temporary but it really is permanent. I am able to sign-in from the web as well as from my iPhone using the same credentials. Can someone help me debug this? TIA