Open Power shell ( Run as Administrator)
Set-OfficewebAppsfarm –SSLOffloaded:$true –AllowHTTP:$true
Restart Office Web App Server (OWAS_ server
Which fixed the above ID prompt
Attaching the standard settings with all OWAS functionality working with Exchange and SharePoint 2013 on Windows Server 2012
I have a internal CA – there my .local url is trusted with my internal CA. and External URL has a trusted cert.