Since Google Drive has made some changes, the template link has been deleted and needs to be added. Here are step-by-step instructions followed by a video showing the same process. (Thanks to Carl Silva for creating these steps!)
1. Go to Google Drive.
2. Click on Create and select Connect more apps at the bottom.
3. In the Search the store field type Template and then hit return.
4. Select Drive Template Gallery by clicking on +Connect.
5. A window will appear stating that the above is connected to Google Drive. Click OK.
You can now add those calendars. How?
1. Go to Create.
2. Select ...from template.