IIS web applications are classified into several types of services, such as 

• Outlook Web Access
• Outlook Anywhere
• Exchange ActiveSync
• Remote Desktop Web Access
• Microsoft Sharepoint
• Citrix Web Interface

Every type of service has a set of pre-configured settings. Therefore, it is important that you select the correct type of service.

For the OWA on Exchange 2016, we select "Outlook Web Access 2016"