Download files from here : https://www.microsoft.com/en-gb/download/details.aspx?id=35554 for your right 64bit or 32bit
Extract the files to a new temp directory, this will create 3 directories and a spreadsheet file (ADM, Admin, ADMX, Office2013GroupPolicyAndOCTSettings.xls)
Now create the directory PolicyDefinitions under: \\your_domain_controller\SYSVOL\your_domain_name\Policies\
It’s easy to do this from your domain controller or just UNC to your sysvol share off your domain controller
Copy all the files that were unzipped in the temp ADMX directory to the new PolicyDefinitions directory you created.
Restart GPMC and either edit or create a new group policy
When the Group Policy Management Editor window comes up, you should see new templates under Administrative Templates.
The folder should state: Administrative Templates: Policy Definitions (ADMX) Retrieved from the Central Store