Could you try the following:
1. Start the Sitefinity 4.0 Project Manager application (latest build recommended)
2. Click on the Create New Project button and complete the next step specifying the project location and name
3. Choose to activate a new license in the next step
4. Provide your mail and password for your Sitefinity account in the next step
5. Choose Community Edition and complete the process.
That should do it. Please let me know if that works or you need additional help!
Grisha 'Greg' Karanikolov
Sitefinity Solutions Consultant