If you create a user group that only have permissions to view devices and maps on only a subset of device groups and/or cameras, but not on the site itself, then users in this group will not be able to view maps. This is because maps belong to the site level, so users must have "view maps" permission on the site.

E.g. This user group has "Operator" permissions only on the "Test 1" device group, so will not be able to see any maps on the site that "Test 1" belongs to even if the "Operator" Role confers "view maps" permissions.

To allow users in this group to view maps, create a new Role that allows Map viewing only;

Then assign this to the user group at the site level;

This user will then be able to view video from the cameras in the "Test 1" device group, and see the maps for the "dave" site, with only the cameras from the "Test 1" device group displayed.