WorkMail : Unable to login to WorkMail on IOS.

I can log in successfully through Android, Mac, and the web, but I'm encountering issues when attempting to log in via iOS.

I've followed the steps outlined in this link to connect the device manually, but I keep receiving an "unable to verify" message.

Here's some additional information about my configuration:

• Auto-discovery is already enabled.
• The default domain provided by AWS is fff.awsapps.com.
• My primary domain is like fffff-ff.com (comprising all alphabets with a single hyphen/dash). This domain is hosted on Route 53.
• I have removed all mobile policies.
• My server region is US East (N. Virginia), us-east-1. However, we are accessing emails from different countries if that information is relevant.

Any assistance you can provide would be greatly appreciated.