Hello
I translate word-to-word, so there may be small differences in your menus (I have a French version)
right-click on Display Fusion tray icon in your windows taskbar& click on desktop wallpaper
a windows open, select your monitor if you are in dual screen
in wallpaper source section on bottom left, tick the box "enable desktop wallpaper slideshow" => interval(minuts) box appears below
you can now enter the interval you want, me i fix to 10 minutes
Of course, don't forget to add one or more folders that contain your desired images
You can verify when you click on apply button, picture change each time you click apply ok ok
Enjoy
(jpg works fine of course)