We were having the same problem.
Solution for us was:
1. on IAAS server log in with AD user ex: domain\iaas-user
2. Start installation as domain\iaas-user
3. On Microsoft SQL server create domain\iaas-user user (General :Windows Authentication , Server Roles: public, serveradmin, sysadmin) - if you can not create AD user domain\iaas-user there is connection problem or SQL server was not joined to the domain.
4. Ensure that you can ping both sql server and iaas server using FQDN on both ends.
5. On IAAS server the installer (Server and account Settings page)
- Local server : use FQDN of IAAS server
- User password : domain\iaas-user and your AD password
- SQL server section use FQDN of SQL server
- Database Name: yourdbname
- select Use Windows Authentication (username and password should be grayed out)
If with this settings you can not go to the next page most likely you have connection problems (Check network, AD and passwords and SQL)
In our case after those checks installation was completed with out any errors.
Good Luck.
Martin.