School email configuration in Apple Mail on OS X 10.13.6

I would like to configure the school email in Apple Mail on OS X 10.13.6 but cannot access the UCS login page in this process.

What I did:
-> go to accounts
-> add Exchange
-> enter credentials
Now I am supposed to get to the UCS login page but I am getting a window which prompts me to enter an “internal URL” and “external URL” instead.