Moon phases for lock screen

[Larsenex]

I know this is a silly thing. I know where the 'add apps' screen is for the lock screen. I went and searched for a simple free app that shows the phases of the moon which I want for the new Windows 10 lock screen. I found one for a $1.99 and two that are free.

I DL'd one of the free ones and it works fine, shows me the Sun and Moon and its phases and such. I am unable to add such app to the lock screen. When I go to the lock screen customization menu and hit +app box it does not show any apps. I assume only certain ones will work here?

So my real question is, does anyone have a simple app that I can use to show the phases of the moon on my lock screen at start up?

Thanks very much!