In the Detailed Error Information section you can see:
Config Error: Cannot add duplicate collection entry of type 'mime Map' with unique key attribute 'fileExtension' set to '.air'
I Googled that error message and found this KB article from Adobe which says:
ColdFusion attempts to register a MimeType, and IIS puts this into a web.config file, and since this entry is actually a duplicate, IIS fails to serve any pages off the affected sites, and throws error 500.19. To fix this issue, navigate to IIS Manager > Site in Consideration > MimeTypes, remove the entry that references .air extension, and reconfigure the connector.
Alternatively, if you're like me and hate inetmgr, you can probably open up web.config and remove that offending line (5, as noted in red).