Sounds pretty complicated compared to the auto slideshow function in 10. In other words, in 10 when I double click an album thumbnail, it goes to Now Playing, starts playing the first track, and starts a slideshow of all scans in that albums directory, It can be viewed full screen by clicking the icon in the lower right, can be paused in the right click menu, and while paused the image can be zoomed in or out using the mouse wheel. The best music playing slideshow I've ever found in ANY music program, and was the reason I originally purchased MC 10 years ago.
The various artwork scans in each albums folder are added into MC by simply dragging and dropping them from Explorer
into the same album folder in MC. Next time that album is played in MC, all added jpg's are automatically shown in the automatic slideshow. Simple, and seemingly, for some reason, removed from MC starting with version 11. Odd.....