From what I can see in the documentation, folder filter expressions can set security based on template field values. Can you also use Tags to apply security in combination with those template field values?
If so, is this the right syntax for a version 9.1 server/client (this came from version 8 documentation, https://support.laserfiche.com/ow.aspx?Laserfiche8.0/FilterExpressions) ?
(IS_GROUP_MEMBER('GroupName') = 1) AND entryprop."FieldName" = 'FieldValue' AND (entryprop.HAS_TAG('Tagname') = 1)