For this step:
Incoming Mail Server. Enter the Zimbra server address. This is typically in the form of mail.example.com. This is the server that your account is on.
... i did enter the one that i use.
actually, i tried a couple.
https://mail.uoguelph.ca/zimbra/ https://mail.uoguelph.ca/
mail.uoguelph.ca
none of them worked. it says 'Please correct missing/invalid input' and highlights 'incoming mail server' in red.
UGH!!!