The administrator's interface for a single digital library that you are looking for is located under /admin URL of your digital library. So if your library is http://my-library.locloudhosting.net/ then the admin interface is located here: http://my-library.locloudhosting.net/admin/. To access it you will need username and password which you provided in the form which you used to create new digital library.
This admin URL for each created digital library is also available in the LoCloud Collections user panel. To view it you need to go to your profile page (https://locloudhosting.net/users/panel). You should see there a table with all digital libraries. Now you need to click DETAILS button visible next to the name of particular digital library. Details page will appear and there will be two links presented: one to public part and second one to admin interface.