Ensure that you have "Imported" the machine and have the latest version of Accuware, to update it:
1. Click on Settings
2. System Settings < Update < Check
If you still cannot find the material option,
3. Locate the file: Material Pack Version, and delete it. Documents< 3DDLP Documents
4. Once the program is booted, a notification to update the material package will appear and update the software.