I believe we have a solution for your case, though it's not fully automated and with a limitation on Mac.
You would need to create a team folder and invite two AD groups to it - one for Collaborators and another for Viewers.
New users added to one of these AD groups will be automatically invited to this team folder.
Users will need to do two actions to get this folder on their local machines for offline use. Both actions are one-time-only for each user during the initial setup.
Each user would need to do two steps:
1) Accept the invitation into a team folder - it should be done in Anywhere User Portal.
2) Mark a specified folder as 'Save Locally' on user's Windows machine.
After invitation is accepted by user, the team folder will be automatically sync'ed to user's Windows machine, but all files in this folder will be stubbed initially (not available for offline use). In order to make them available for offline use, a user would need to mark this folder as 'Save Locally' in Windows File Explorer. It requires two clicks in Windows Explorer: right click on a folder, and select 'Save Locally' option and click.
The 2nd step for Mac users is different:
2) As in step 1, it'll be done in Anywhere User Portal: set 'Sync' option for the team folder in question.
It will start the download of all files from HCPAW into user's Mac machine (Mac must be registered with HCPAW).
The limitation for Mac is that users with a 'Viewer' role won't be able to download files to Mac machines. Ability to download files from HCPAW to Mac is only available for users with a 'Collaborator' role.