Seems like initial configuration expects you to login with a username and pw/key you chose during setup:
The Bitnamic Subversion on Azure page indicates the the username to use is
bitnami
.It also has a link to a page entitled "How to connect to my (Windows Azure) server" which says:
Enter your login and password that you already configured from the Azure wizard. The example below shows "bitnami" user but your user could be different.
That references the "Azure wizard"; there's another link to "Azure Cloud - Getting Started" that has a screen shot like this:
Note particularly the option to Upload ssh key for authentication