Hide all listings (except for admin)

I´m using Directory 8.9. I would like businesses to register and signup for our newsletter. They should also select their location on GoogleMaps.

However I don’t want anybody to see all these registered users on the map. The only one that should be able to see the map and all the users on it, is Admin.

I tried to make the page passwordprotected but it doesn’t seem to work.

Any ideas ?

If you visit vrachtalert.nl you can see the registered members. I want them to be visable to me only.