On the local computer, do the following:
1. Right Click on My Computer
2. Select Manage
3. Scroll to Local User and Groups and under Groups;
4. Double click on Administrators
5. Search for the Account (from your AD) you want to enable as a local Administrator
6. Click Add…that’s it!
PS. You can simply add ‘Domain Users’ to avoid each time adding a User in the Administrative Group.