Follow instructions in the screenshots below.
Open Settings app. Select Accounts & Passwords.
Select Add Account.
Select Exchange.
Enter your work username followed by @lyndendoor.com (Your user name is the first letter of your first name and up to seven of your last i.e. abrim, slargent, or msamouko) and a description.
Select Sign In at the prompt.
Select any additional options you would like to sync to your phone from the work account and select Save.