Sync AD Group to XGS

I would like to import an on prem Active Directory Security Group into my Sophos XGS 6500.  I already have AD sync'd with the XGS and that is functioning.  I attached a different AD Security Group to an XGS group at one point, but I cannot figure out how to replicate what I did back then.  I know I need to create a local group on the XGS, and then somehow attach the AD group, which will then populate as I add and remove members, but how do I add that AD group to the local group I created?  Any assistance would be appreciated. 

on SFOS 21.0.0 Build 169