The circle in the upper left corner of the window should toggle the different views, which should open up the armor slots.
When in doubt, check out the ". . . " button next to each of the mods in the updater
P.S. If you don't like the window (or any of them for that matter), you can easily grab another author's mod and it will work without any issues. Just make sure you uncheck the window within the updater and/or mark the "Do Not Update if local file is newer" on the Options tab.