By default, the administrator login and password are admin: admin
If you are using AWS, before resetting your administrator password, try using the AWS instanceId as your password.
The administrator password is stored encrypted in the database.yml file. (/usr/local/FlashphonerWebCallServer/conf/database.yml)
You can also change password there. To change, specify a new md5 encrypted password in the "admin" user line.
I will try. once I type any password I get a web authorization window as well. I don't think we're using any proxy - so I'm not sure if it's your code or something else - but would it be the same password ?