HELP: can't login client computer, exchange server 2016

So I need to setup an exhange mail server for a school task. I need to be able to login on a windows client with an exchange account. I did everything right, installed the exchange server and connected the windows client to my domain "sendit.be".

But am not able to login on my exchange account on my windows client (see screenshots)

I hope someone can help me. Thank you in advance!