- I dowloaded the software (without source code) and I uploaded it via FTP in the root of my website. - I prepared the MSSQL db. - I setted write permissions. - I have'nt Visual Studio, so I writed directly www.mysite.it/install/
I think your server is running IIS 6. Are you absolutely sure you have support on your server for ASP.NET MVC 3 and the Microsoft .NET Framework version 4?
Think you need to check with them that the server your site is running on really does support both .NET 4 AND MVC 3.
It does look as if your server is running IIS 6 and so may not have all the latest Micrsoft components and services installed on it. You need to ask them.