Hello Jenny Teague,
Project Manager requires IIS 6 compatibility installed - this might be the reason for the 404 Error.
Can you try this instead:
1. Download from your Client.net account Sitefinity 3.6
- Blank Project zip.
2. Extracted on your local hard drive (c:\SitefinityProject for exmple)
3. Open the IIS and "Add Application" under the "Default Web Site"
4. Choose site "Alias" then map Sitefinity's folder as site "Physical Path" and use your "Default Application Pool"
5. Open IE and navigate "http://localhost/[YourSite Alias]/sitefinity/cmsstartup.aspx
Hope this helps.
the Telerik team