Hi Ricardo Santos,
Thank you for using our services.
The Project Manager that used for creation of projects has to run in a Full Trust mode, otherwise you will not be able to create your projects. Can you please check the .NET Trust Levels of the Sitefinity 3.6 web application in IIS Manager (see attached image). It has to be set on Full
trust. Furthermore you can take a look at the Bullet Proof Guide to Installing Sitefinity 3.x
for further configurations that you might have to do to the IIS, if you already have not done so.
I hope that the provided information will help you create your project. If you have questions, please feel free to contact us.
the Telerik team