When using the service request Request->Membership->Local administrator it is necessary that Process Manager account is local administrator on the client you are trying to request local admin on. The workflow can look like this if you have not setup this the correct way:
If you setup the Process Manager the correct way and it still does not work, the you can try to disable the firewall on the client and try again.
If it still does not help after doing this i suggest that you contact productsupport@atea.com as they will try to help you out.
Good luck.