Use the Permission interface FileDownload property to determine if group or client has permission to download from a folder, and to allow or deny downloading permisson.
Signature:
HRESULT FileDownload([out, retval] VARIANT_BOOL *pVal);
HRESULT FileDownload([in] VARIANT_BOOL newVal);
True = Allowed
False = Prohibited
Refer to Permission Interface Properties for an illustration of how this and other Permission properties can be accessed in the Administrator interface.