RAC (Revoke Access Control) can be enabled for roles through the Permissions tab and not on content in the Documents tab. 

If it should only apply to some specific files within the data room:

1. enable RAC for a role in Download Options.
2. Set the permission for a file to Download.
3. The permissions for other content should be set to Hidden or View. 

If a role should be able to download other content without RAC applied to downloadable files, Native File Download can be selected.