By default the plug-in hides group names in parts. E.g. on a piano part the "Piano" name left to the staff lines (=group name) will be hidden, so that only the part name is visible.
If the part doesn't have a page text object with the part name, the group name will not be hidden.
For better readability group brackets are can be automatically added to staff groups with at least three staves (Option: "Add Group Brackets on Groups with at Least 3 Staves").
The plugin makes sure that these groups don't interfere with other groups or other group brackets and in doubt it won't add a bracket.