image size of slide

Hello team

I′m like this plug in. And up to know I had I′m using the free version.
But now I want to have the image slide like this
https://www.metaslider.com/examples/image-slides/

different size of pictures in one slideshow. Is this possible with this free version. and if yes, what do I wrong with my settings.
I would like these white background right and left if the image has not the same widht. The height I suppose must be the same.

this is the link were I′m trying with the show.
https://test-wp01.xn--binder-grten-ncb.de/?p=568

I hope somebody can help me.
I also would buy the pro version if not possible.
thanx
Marga

https://www.ads-software.com/plugins/ml-slider/