...
Collections is another way of grouping workbooks together that might be in different project folders.
A Collection does not have any permissions structure, it is only a shortcut to a specific workbook or sheet. only has permissions to see the collection itself. The shortcuts to workbooks are subject to the permissions for the workbook or containing Project.
The permissions are controlled by the Project, Datasource, Workbook, Worksheet settings.
Three different people might see three different results when looking at the same collection.
...