How to add Computers to Policy by default?

I like many have cloned the default policies and created a set of "Base Policies" which have been edited to fit our needs.

At present we have created a new Computer Group that is applied to all these new "Base Policies" I have created. During our testing phase we have been adding computers to this Computer Group to ensure they have all the correct policies applied.

I would now like to automate this process so all new devices that are enrolled in Sophos get the new Policies applied by default without needing to do any manual steps. I have been told by Support the easiest way to do this is via the AD Sync tool which I have installed on-prem. The Sync Tool is restricted to only Syncing our new OUs with new devices in.

I have been unable to work out how to configure the AD Sync Tool to place the Computers in the relevant Group within Sophos. I have gone back to support but not heard anything yet and am worried I have installed AD Sync for no reason! Can someone clarify how to have my newly protected devices pick up the right policies automatically?

Thanks all,