METHOD 1
1) Find and open the default mail app that comes installed on the apple device.
2) You'll be given a list of account hosts, Out of the options select the exchange.
3) Enter your ATC email and password while leaving everything else blank. Double check the spelling and select "Done"
4) In a few moments it will have found the server and initialized the connection.
ps. try method 1 completely before bothering with method #2
METHOD 2
1) Follow process A up until step "3"
2) Enter in your ATC email account information, and instead of leaving the rest blank it will ask for either IMAP or POP server, or both.
3) In both of the server input sections enter "outlook.office365.com" and select "Done"
4) after a few moments the server connection will be initialized and finished.
PS. In your iPhone settings, under the "Mail" tab, you can change the refresh rate, id recommend somewhere around 30 mins.